user invalid login
<p>I am creating my own website just to get some experience. I've been working on it for 3 days and am at the point where I can sign up and sign in.</p>

<p>When signing in, if the combination of the username and password is not found in the database, my code displays an error message telling the user that either he didn't sign up yet or he is entering a wrong user email or password.</p>

<p>But, the message  is displayed in a new page, instead of the sign in page. </p>

<p>I looked at some tutorials online, but didn't find a good explanation for it. Could someone please give me some advise? </p>

<p>I am using PHP for the database connection.</p>
