index.html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<body>
<form method="POST" action="strona.php">
<label for="marka">Marka</label>
<input type="text" name="marka">
<label for="model">Model</label>
<input type="text" name="model">
<label for="rok">Rok</label>
<input type="number" name="rok">
<input type="submit" value="Wyślij">
</form>
</body>
</html>strona.php
<?php
$connect=mysqli_connect('localhost','root','','salon');
$marka=$_POST['marka'];
$model=$_POST['model'];
$rok=$_POST['rok'];
$sql="INSERT INTO samochody VALUES (NULL, '$marka', '$model', $rok);";
$query=mysqli_query($connect,$sql);
echo $marka;
echo $model;
echo $rok;
mysqli_close($connect);
?>