Как сделать форму отправки авторизации?

Выдает ошибку:Warning: mysqli_num_rows() expects parameter 1 to be mysqli_result, boolean given in /storage/emulated/legacy/htdocs/circle.php on line 12;
Код:

<?php
echo "Ваш логин: ". $_GET["username"]."<br>";
echo "Ваш пароль: ".$_GET["password"];
$db = mysqli_connect('localhost', 'root','', 'Page');
if($db == false){
echo mysqli_connect_error();
exit();
}
$login = $_GET["username"];
$password = $_GET["password"];
$count = mysqli_query($db, "SELECT * FROM 'Users' WHERE 'login' = '$login' AND 'password' = '$password'");
if(mysqli_num_rows($count) == 0){
echo "You aren't signed";
}else{
echo "You are signed";
}
?>