<?php
namespace yourmodulenamespaceHelper;
class Create extends MagentoFrameworkAppHelperAbstractHelper
{
     /**
    * @param MagentoFrameworkAppHelperContext $context
    * @param MagentoStoreModelStoreManagerInterface $storeManager
    * @param MagentoCatalogModelProduct $product
    * @param MagentoFrameworkDataFormFormKey $formKey $formkey,
    * @param MagentoQuoteModelQuote $quote,
    * @param MagentoCustomerModelCustomerFactory $customerFactory,
    * @param MagentoSalesModelServiceOrderService $orderService,
    */
    public function __construct(
        MagentoFrameworkAppHelperContext $context,
        MagentoStoreModelStoreManagerInterface $storeManager,
        MagentoCatalogModelProduct $product,
        MagentoFrameworkDataFormFormKey $formkey,
        MagentoQuoteModelQuoteFactory $quote,
        MagentoQuoteModelQuoteManagement $quoteManagement,
        MagentoCustomerModelCustomerFactory $customerFactory,
        MagentoCustomerApiCustomerRepositoryInterface $customerRepository,
        MagentoSalesModelServiceOrderService $orderService,
        MagentoQuoteModelQuoteAddressRate $shippingRate
    ) {
        $this->_storeManager = $storeManager;
        $this->_product = $product;
        $this->_formkey = $formkey;
        $this->quote = $quote;
        $this->quoteManagement = $quoteManagement;
        $this->customerFactory = $customerFactory;
        $this->customerRepository = $customerRepository;
        $this->orderService = $orderService;
        $this->shippingRate = $shippingRate;
        parent::__construct($context);
    }

    /**
     * Create Order On Your Store
     *
     * @param array $orderData
     * @return array
     *
    */
    public function createMageOrder($orderData) {
        $store=$this->_storeManager->getStore();
        $websiteId = $this->_storeManager->getStore()->getWebsiteId();
        $customer=$this->customerFactory->create();
        $customer->setWebsiteId($websiteId);
        $customer->loadByEmail($orderData['email']);// load customet by email address
        if(!$customer->getEntityId()){
            //If not avilable then create this customer
            $customer->setWebsiteId($websiteId)
                    ->setStore($store)
                    ->setFirstname($orderData['shipping_address']['firstname'])
                    ->setLastname($orderData['shipping_address']['lastname'])
                    ->setEmail($orderData['email'])
                    ->setPassword($orderData['email']);
            $customer->save();
        }
        $quote=$this->quote->create(); //Create object of quote
        $quote->setStore($store); //set store for which you create quote
        // if you have allready buyer id then you can load customer directly
        $customer= $this->customerRepository->getById($customer->getEntityId());
        $quote->setCurrency();
        $quote->assignCustomer($customer); //Assign quote to customer

        //add items in quote
        foreach($orderData['items'] as $item){
            $product=$this->_product->load($item['product_id']);
            //$product->setPrice($item['price']);
             $product->setWeight(20);
            $quote->addProduct(
                $product,
                intval($item['qty'])
            );
        }

        //Set Address to quote
        $quote->getBillingAddress()->addData($orderData['shipping_address']);
        $quote->getShippingAddress()->addData($orderData['shipping_address']);

        // Collect Rates and Set Shipping & Payment Method

        $shippingAddress=$quote->getShippingAddress();

        /*$shippingAddress->setCollectShippingRates(true)
                        ->collectShippingRates()
                        ->setShippingMethod('fedex_FEDEX_GROUND'); //shipping method

        */
        //$this->shippingRate
          //  ->setCode('fedex_FEDEX_GROUND');
            //->getPrice(1);
        //$shippingAddress = $cart->getShippingAddress();
        //@todo set in order data
        $shippingAddress->setCollectShippingRates(true)
            ->collectShippingRates()
            ->setShippingMethod('fedex_FEDEX_GROUND'); //shipping method
        //$quote->getShippingAddress()->addShippingRate($this->shippingRate);
        $quote->setPaymentMethod('checkmo'); //payment method
        $quote->setInventoryProcessed(false); //not effetc inventory
        $quote->save(); //Now Save quote and your quote is ready

        // Set Sales Order Payment
        $quote->getPayment()->importData(['method' => 'checkmo']);

        // Collect Totals & Save Quote
        $quote->collectTotals()->save();

        // Create Order From Quote
        $order = $this->quoteManagement->submit($quote);

        $order->setEmailSent(0);
        $increment_id = $order->getRealOrderId();
        if($order->getEntityId()){
            $result['order_id']= $order->getRealOrderId();
        }else{
            $result=['error'=>1,'msg'=>'Your custom message'];
        }
        return $result;
    }
}

array (
  'request' =>
  array (
    'WebAuthenticationDetail' =>
    array (
      'UserCredential' =>
      array (
        'Key' => '****',
        'Password' => '****',
      ),
    ),
    'ClientDetail' =>
    array (
      'AccountNumber' => 'XXXXXX',
      'MeterNumber' => '****',
    ),
    'Version' =>
    array (
      'ServiceId' => 'crs',
      'Major' => '10',
      'Intermediate' => '0',
      'Minor' => '0',
    ),
    'RequestedShipment' =>
    array (
      'DropoffType' => 'REGULAR_PICKUP',
      'ShipTimestamp' => '2017-06-27T06:09:23+00:00',
      'PackagingType' => 'YOUR_PACKAGING',
      'TotalInsuredValue' =>
      array (
        'Amount' => 0,
        'Currency' => 'USD',
      ),
      'Shipper' =>
      array (
        'Address' =>
        array (
          'PostalCode' => '90034',
          'CountryCode' => 'US',
        ),
      ),
      'Recipient' =>
      array (
        'Address' =>
        array (
          'PostalCode' => '11701',
          'CountryCode' => 'US',
          'Residential' => false,
          'City' => 'Ave Forest Hills',
        ),
      ),
      'ShippingChargesPayment' =>
      array (
        'PaymentType' => 'SENDER',
        'Payor' =>
        array (
          'AccountNumber' => 'XXXXX',
          'CountryCode' => 'US',
        ),
      ),
      'CustomsClearanceDetail' =>
      array (
        'CustomsValue' =>
        array (
          'Amount' => 0,
          'Currency' => 'USD',
        ),
      ),
      'RateRequestTypes' => 'LIST',
      'PackageCount' => '1',
      'PackageDetail' => 'INDIVIDUAL_PACKAGES',
      'RequestedPackageLineItems' =>
      array (
        0 =>
        array (
          'Weight' =>
          array (
            'Value' => 0.0,
            'Units' => 'LB',
          ),
          'GroupPackageCount' => 1,
        ),
      ),
      'ServiceType' => 'SMART_POST',
      'SmartPostDetail' =>
      array (
        'Indicia' => 'PRESORTED_STANDARD',
        'HubId' => NULL,
      ),
    ),
  ),
  'result' =>
  stdClass::__set_state(array(
     'HighestSeverity' => 'ERROR',
     'Notifications' =>
    stdClass::__set_state(array(
       'Severity' => 'ERROR',
       'Source' => 'crs',
       'Code' => '809',
       'Message' => 'Package 1 - Weight is missing or invalid. ',
       'LocalizedMessage' => 'Package 1 - Weight is missing or invalid. ',
       'MessageParameters' =>
      stdClass::__set_state(array(
         'Id' => 'PACKAGE_INDEX',
         'Value' => '1',
      )),
    )),
     'Version' =>
    stdClass::__set_state(array(
       'ServiceId' => 'crs',
       'Major' => 10,
       'Intermediate' => 0,
       'Minor' => 0,
    )),
  )),
) {"is_exception":false} []

$orderData = [
     'email'        => 'ram10test@gmail.com', //buyer email id
     'shipping_address' =>[
            'firstname'    => 'Ramki ', //address Details
            'lastname'     => 'ram',
                    'street' => '10119 Ascan Ave Forest Hills',
                    'city' => 'Ave Forest Hills',
            'country_id' => 'US',
            'region' => '43',
            'postcode' => '11701',
            'telephone' => 'XXXX',
            'fax' => '32423',
            'save_in_address_book' => 1
                 ],
   'items'=> [ //array of product which order you want to create
              ['product_id'=>'2','qty'=>1]
            ]
];