np

<!DOCTYPE html>
<?php
require_once 'neco.php';
if (isset($_POST["submit"])) {
    $nazev = $_POST["nazev"];
    $cislo = $_POST["cislo"];

    $neco = new neco($nazev, $cislo);
    $neco->insertNeco();
}
?>
<html>
    <head>
        <meta charset="UTF-8">
        <title>neco</title>
    </head>
    <body>
        <form method="post">
            Nazev<input type="text" name="nazev"><br>
            Cislo<input type="number" name="cislo"><br>
            <input type="submit" value="submit" name="submit">
        </form>
    </body>
</html>

--------------------

<?php

class neco {

    public $nazev;
    public $cislo;

    function __construct($nazev, $cislo) {
        $this->nazev = $nazev;
        $this->cislo = $cislo;
    }

    function insertNeco() {
        $vloz = $this->connect()->prepare("INSERT INTO `neco` (`nazev`, `cislo`) VALUES (?, ?)");
        $vloz->bindParam(1, $this->nazev);
        $vloz->bindParam(2, $this->cislo);
        $vloz->execute();
    }

    function connect() {
        $dsn = "mysql:dbname=neco;host=localhost";
        $user = "root";
        $password = "";

        $conn = new PDO($dsn, $user, $password);

        return $conn;
    }

}