help with login screen (splitted)

[zero_ZX]

Hi there! i want to split my vb login, into two parts, where you first enter your username, then alot of detials comes up, such as: group, posts, join date, account name, avatar.
Then below you will enter your password.

I have already coded a very little piece of the code, but i dont know the sql very well, and i have some troubles intigrating it to vbulletin.. if some1 out there can help me, i would love it.

here the code ive already got:

PHP Code:

<?php
//SPLIT script imprented

// first, let's see what step they're on...
$step = $_GET['step'];

// if a user is allready logged in, and he's not trying to log out, he has no bussiness on this file
if ( $step != 'logout' && $_SESSION['login'] === TRUE )
{
 $step = 'loggedin';
}


switch($step)
{
//if step is not defined in the url, then they're going to this step
default:
case '1': 
 
 // ask for username
 echo '<form action="login.php?step=2" method="POST">
 Username : <input type="text" name="username">
 <br> <input type="submit" value="Log me in">
 </form>';
 
break;

case '2':
 // get username from step 1
 $username = $_POST['username'];
 
 // now ask for the password
 echo '<form action="login.php?step=3" method="POST">
 Password : <input type="password" name="password">
 <input type="hidden" name="username" value="'.$username.'"> 
 <input type="submit" value="submit">';
 
break;

case '3':
 // get username and password from step two
 $username = $_POST['username'];
 $password = $_POST['password'];
 
 // connect to database, however you do it.. i use
 require_once("DbConnect.class.php");  
 // define query
 $sql = "SELECT username, password FROM users WHERE username =".$username." AND password =".$password."GROUP BY username";
 if ( !$results = mysql_query($sql)) {
  die('Username or password are incorrect!');
 }
 else {
  $_SESSION['data'] = mysql_fetch_assoc($results);
  $_SESSION['login'] = TRUE;
 
 
 break;
 
case 'loggedin':
 echo "You are allready logged in.";
break;

case 'logout':
if ( $_SESSION['login'] === TRUE )
 {
  if ( isset($_COOKIE[session_name()]) )
  {
   setcookie(session_name(), '', time()-42000, '/');
  }
 
  foreach ( $_SESSION as $k=>$v )
  {
   unset($_SESSION[$k]);
  }

  session_destroy();
  echo "You've successfully logged out!";
 }
break;

}
?>