PHP login/Register errors

Ok I have been asked by my college lecturer to create a login system using PHP. Now I read up about PHP seeing as Im not familiar to it. I used this code and coded some myself.

session_start();

$username = $_POST ['username'];
$password = $_POST ['password'];

if ($username&&$password) {

    $connect = mysql_connect("localhost","root","") or die("Couldn't Connect");
    mysql_select_db("phplogin") or die ("Couldn't find Database");
    $query = mysql_query("SELECT * FROM users WHERE username='$username'")'
     $numrows = mysql_num_rows ($query);
if ($numrows!=0) {

    while ($row = mysql_fetch_assoc()) {
        $dbusername = $row['username'];
        $dbpassword = $row['password'];
    }


    if ( ($username==$dbusername) && ($password==$dbpassword) ) {
        echo "you are in, Click here to enter member page";
        $_SESSION['username']=$dbusername;
    } else {
        echo "Incorrect password";
} else {
    die ("That user does not exist");
}
echo $numrows;


} else {
    die("Please enter a username and password")
}

?>

This is the Index.php I am using.
My login page is simple with 2 fields: Username and Password, with a login and register button.

Once I enter details into the fields that I have taken from my database, it displays this at the very top of the page.

Click here to enter member page"; $_SESSION['username']=$dbusername; } else echo "Incorrect password"; } else die ("That user does not exist"); echo $numrows; } else die("Please enter a username and password") ?>

I also have a problem with my register page which has 4 fields that you MUST fill in: Username, Email, Password and Confirm Password, along with a Register button to "Register" as a user.

//form data $name = strip_tags ($_POST['name']); $username =
strip_tags ($_POST['username']); $password = md5 (strip_tags
($_POST['password'])); $confirmpassword = strip_tags
($_POST['confirmpassword']); $date = date("Y-m-d");

if ($submit) {

if ($username&&$password&&$confirmpassword) { //encrypt password

$password = md5 ($password); $confirmpassword = md5
($confirmpassword);
if ($password==$confirmpassword) { //check character length if (strlen ($username) >25 || strlen ($name) >25) { echo
"length of Username or Name is too long"; } else {
//checks password length
if (strlen ($password) >20||strlen($password)<5)
{
echo "password must be between 5 and 20 characters";
}
else

{
//registers user
} } } else echo "Your passwords to not match!";

      }           else        echo "Please fill in all feidls!"; } ?>

Your full Name:





Choose a Username:






Choose a Password:





Confirm your Password:

HOWEVER, even before entereing detail to hte fields, this large bulk of code appaears at the top of the page.

25 || strlen ($name) >25) { echo "length of Username or Name is too long"; } else { //checks password length if (strlen ($password) >20||strlen($password)<5) { echo "password must be between 5 and 20 characters"; } else { //registers user } } } else echo "Your passwords to not match!"; } else echo "Please fill in all feidls!"; } ?>

Can someone please tell me what I have done wrong here? I use Xampp to make my database.