Hello , I'm in some trouble regarding the following code.I must state first that I'm a beginner in programming, and that I've tried to understand other solved solutions before crying for help , but with no luck.Had tons of errors and a lot of frustration ; almost gave up(work on other stuff too that give me headaches).Though , I need to pull this off , it's for an important project of mine.If you're willing to help I'll be eternal gratefull.SO ..here is the code :

config.php (which has the db settings)

<?php
    //set off all error for security purposes
    error_reporting(E_ALL);


    //define some contstant
    define( "DB_DSN", "mysql:host=localhost;dbname=clients" );
    define( "DB_USERNAME", "root" );
    define( "DB_PASSWORD", "" );
    define( "CLS_PATH", "class" );

    //include the classes
    include_once( CLS_PATH . "/user.php" );


?>

users.php (which has the functions for the system to work)

<?php

 class Users {
     public $username = null;
     public $password = null;
     public $salt = ""

     public function __construct( $data = array() ) {
         if( isset( $data['username'] ) ) $this->username = stripslashes( strip_tags( $data['username'] ) );
         if( isset( $data['password'] ) ) $this->password = stripslashes( strip_tags( $data['password'] ) );
     }

     public function storeFormValues( $params ) {
        //store the parameters
        $this->__construct( $params ); 
     }

     public function userLogin() {
         $success = false;
         try{
            $con = new PDO( DB_DSN, DB_USERNAME, DB_PASSWORD ); 
            $con->setAttribute( PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION );
            $sql = "SELECT * FROM users WHERE username = :username AND password = :password LIMIT 1";

            $stmt = $con->prepare( $sql );
            $stmt->bindValue( "username", $this->username, PDO::PARAM_STR );
            $stmt->bindValue( "password", hash("sha256", $this->password . $this->salt), PDO::PARAM_STR );
            $stmt->execute();

            $valid = $stmt->fetchColumn();

            if( $valid ) {
                $success = true;
            }

            $con = null;
            return $success;
         }catch (PDOException $e) {
             echo $e->getMessage();
             return $success;
         }
     }

     public function register() {
        $correct = false;
            try {
                $con = new PDO( DB_DSN, DB_USERNAME, DB_PASSWORD );
                $con->setAttribute( PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION );
                $sql = "INSERT INTO users(username, password) VALUES(:username, :password)";

                $stmt = $con->prepare( $sql );
                $stmt->bindValue( "username", $this->username, PDO::PARAM_STR );
                $stmt->bindValue( "password", hash("sha256", $this->password . $this->salt), PDO::PARAM_STR );
                $stmt->execute();
                return "Registration successful! <br/> <a href='index.php'>Login.</a>";
            }catch( PDOException $e ) {
                return $e->getMessage();
            }
     }

 }

?>

login.php

<?php 

include_once("config.php"); //include the settings/configuration
?>

//if user did not click the login button show the login form
<?php if( !(isset( $_POST['login'] ) ) ) { ?>

<!DOCTYPE htmude_once("config.php"); //include the settings/configuration
?>

//if user did not click the login button show the login form
<?php if( !(isset( $_POST['login'] ) ) ) { ?>

<!DOCTYPE html>
<html>
    <head>
        <title>Codecall Tutorials - Secured Login with php5</title>
        <link rel="stylesheet" type="text/css" href="style.css" />
    </head>

    <body>

        <header id="head" >
         <p>Codecall tutorials User Login</p>
         <p><a href="register.php"><span id="register">Register</span></a></p>
        </header>

        <div id="main-wrapper">
         <div id="login-wrapper">
             <form method="post" action="">
                 <ul>
                     <li>
                         <label for="usn">Username : </label>
                         <input type="text" maxlength="30" required autofocus name="username" />
                     </li>

                     <li>
                         <label for="passwd">Password : </label>
                         <input type="password" maxlength="30" required name="password" />
                     </li>
                     <li class="buttons">
                         <input type="submit" name="login" value="Log me in" />
                            <input type="button" name="register" value="Register" onclick="location.href='register.php'" />
                     </li>

                 </ul>
             </form>

            </div>
        </div>

    </body>
</html>

<?php 
//else look at the database and see if he entered the correct details
<?php 
} else {
    $usr = new Users;
    $usr->storeFormValues( $_POST );

    if( $usr->userLogin() ) {

    header("Location:personal.php");



    } else {
        echo "Incorrect name /password.";   
    }
}
?>

This is 'stock' code with no modification.What I tried to implement is that after a username logs in , he will be redirected to the following pages BASED ON DATABASE , "clients" table userID.
So: if username is George (id=35) upon successful login, he will be redirected to "admins.php" .If his name is Troll (id=5), upon succesfull login he will be redirected to "personal.php".I will be setting the admin's id's manually in the script.
Thank you for taking interest in my problem.

You don't actually say what your problem is - are you looking for SQL code or do you have an error message?

switch($id) {
    case: 5 :
        header('location: /personal.php');die;
        break;
    case 35 :
        header('location: /admins.php');die;
        break
    }
}

Within your Users class, you could implement a handling method that returns the required page based upon the user ID. The method could look something like the following:

Class Users
{
    private $adminIDs = [1, 2];

    /* class methods here */

    public function whereToGo($userID)
    {
        if(in_array($userID, $this->adminIDs, TRUE)) {
            return 'admins.php';
        }
        return 'personal.php';
    }
}

Then within the client-calling code, you would modify the header relocation to the following:

header("Location:{$usr->whereToGo($userID)}");

How you get the user ID is up to you. I personally would get it within your userLogin function since you're returning the entire tuple from the parametrised query (with the asterisk wild card). From there, you could assign it to a property within your class, which would allow you to omit the single argument within the whereToGo() function.

Yes , I'm looking how to implement the code .I'm really sorry for asking what you think they are 'basic things' but I'm really trying to learn ..in a short time.