How can i create new topic with using php

Firstly sorry for my bad english i hope u understand me.

Im working with a project with using PHP and HTML.

I want to create a blog so im working on a create admin panel.

I can already creating a topic but when i want to create one more it doesn't work it just editing first topic.

Screenshots are here: When i create first topic: http://prntscr.com/ihm637

When i try to enter one more topic: http://prntscr.com/ihm6lc

    Admin Panel's codes
 <?php
      if(isset($_POST['headline'])){
        $_SESSION['headline']=$_POST['headline'];
        $_SESSION['shortdesc']=$_POST['shortdesc'];
        $_SESSION['longdesc']=$_POST['longdesc'];
        $_SESSION['photolink']=$_POST['photolink'];
        $_SESSION['saved']=false;

}
        ?>

---.

And index's codes are here
    <div class="content-grid">
                 <?php
        //If topic didnt saved to web page do the following actions
                        if (isset($_SESSION['saved'])) {
                         if($_SESSION['saved']==false){

                echo <<<EOT
                <div class="content-grid-info">
                 <img src="$_SESSION[photolink]"/>
                 <div class="post-info">
                     <h4><a href="single.html"> $_SESSION[headline]  </a>  $_SESSION[date]  </h4>
                     <p> $_SESSION[shortdesc] </p>
                     <a href="single.html"><span></span>READ MORE</a> -->
                    </div>
                </div>
EOT;

                        }
                    }
                    $_SESSION['ready']=true;
                 ?>
                 </div>

Feel free to ask u dont understand it.Hope can somebody can help me.

Have a good day for all.