Untitled

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">

<html>
<head>
 <TITLE>Welcome</TITLE>
</head>
<body>
 <form action="" method=POST>
 <div>
 <strong>Username:</strong><input type="text" name="username" value=""><br/>
 <strong>Password:</strong><input type="password" name="password" valuse=""><br/>
 <input type="submit" name="submit" value="Submit"><br/>
 </div>
 </forum>
<?php
  session_start();
  echo "Hello world!";
  include('sql_connect.db.php');
  if(isset($_POST[submit])){
  $uname=$_POST['username']
  $pass=$_POST['password']
  }
  $result = mysql_query("SELECT * FROM users WHERE username=$uname")
  $row=mysql_fetch_array($result);
  $flag=0
  if($row)
   $usp=$row['password']
   if (pass==usp){
   $_SESSION['login_user'] = $uname;
   header("location: success.php");
   }else {
        $error = "Your Login Name or Password is invalid";
      }
  ?>
 </body>
</html>