<form method="post" action="">
<p>user name</p>
<input type="text" name="name" placeholder="user name"/>
<p>password</p>
<input type="password" name="pasbox" placeholder="password"/>
<br><br><br>
<input type="submit" value="enter" name="submit"/><br><br>
</form>

...

<?php

    // to connect to d.b
    require_once '../conection/connect.php';

    $urNam=$_POST['name'];
    $pass=$_POST['pasbox'];
    // check with database

    if($urname == adminName && $pass == adminPass){

        enter to the admin speace

    }else{

        user name and/or password are not right!

    }

function func_name()
{
    require_once '../conection/connect.php';
    $urNam= $_POST['name'];
    $pass= $_POST['pasbox'];
    $sql = "SQL HERE";
    $query = mysqli_query($mysqli_conn,$sql);
    $row = mysqli_num_rows($query);
    if ($row == 0) {
        echo "<span class='alert alert-danger' style='position:absolute; width:100%'>Wrong Username/Password Combination</span>";
    }
    elseif($urname == adminName && $pass == adminPass){
        $fetch = mysqli_fetch_array($query);
        $type = $fetch['user_role'];
        $name = $fetch['username'];
        if ($type == "Administrator") {
            @session_start();
            $_SESSION['user_role'] = $type;
            $_SESSION['admin'] = $name;
            header("Location: admin/index.php");
        }