$_SESSION and security

[Lodius2000]

so I have my login page that once a valid username is compared to the users in the database it writes that user to $_SESSION['username'], how do i go from simply writing a username into a session, to making that session into something that is required to display pages below the login page, say for altering or creating a blog post.

 

would it just be something like

 

<?php
session_start();

if ($_SESSION['username']){
     display_page();
} else {
     print '<a href="login.php">Login first dummy</a>

 

or something more complicated?

 

Thanks in advance

[dezkit]

<?php
session_start();

if ($_SESSION['username']){
     display_page();
} else {
     echo "<a href='login.php'>Login first dummy</a>";
?>

 

hilol