Switch login form to logout form once logged in...

This is the code im using for the forms, so far the forms are on defferent pages ( because and can't get the if/else to work ), when i use the code in this link "http://www.plus2net.com/php_tutorial/php_login_logout.php

" i add the code to one page but it just doesnt work...

This is on the page i want to use as the main template. Do i need more files for this to work?

<div id="header">

    <table width="100%" cellpadding="5">

      <tr>

        <td width="1022"><table>

          <tr>

            <td class="tablebg">Gamers</td>

          </tr>

        </table></td>

        <td width="300" rowspan="2" align="right" nowrap="nowrap">

<?

if(isset($session[MM_Username])){  // Member is logged in so we have to display welcome message with userid and one logout link

echo "

<form id="form1" name="form1" method="post" action="">

          <p> Welcome <?php echo $_SESSION['MM_Username']; ?>! <a href="<?php echo $logoutAction ?>">

            <input type="button" name="log out" id="submit" value="Log Out!" /></a> </p>

</form>";

}else {  // Member has not logged in so we can display the login form allowing member to login with user id and password

echo "<form id="form1" name="form1" method="POST" action="<?php echo $loginFormAction; ?>">

          <p>

            <label for="username">Username/E-Mail</label>

            <input type="text" name="username" id="username" />

          </p>

          <p>

            <label for="password">Password</label>

            <input type="text" name="password" id="password" />

          </p>

          <p>

            <a href="../register.php"><input type="button" name="register" id="register" value="Register Now!" /></a>

            <input type="submit" name="submit" id="submit" value="Login!" />

          </p>

        </form>";

}    // End of else condtiion echo "</table>";  (i dont get this </table> tage here)

?>

</td>

      </tr>

      <tr>

        <td><ul id="MainNav" class="MenuBarHorizontal">

          <li><a href="../home.php">Home</a></li>

          <li><a href="#">Forum</a></li>

          <li><a href="#" class="MenuBarItemSubmenu">Games</a>

            <ul>

              <li><a href="#">C.O.D</a></li>

              <li><a href="#">CounterStrike</a></li>

              <li><a href="#">Planetside</a></li>

            </ul>

          </li>

          <li><a href="#">Members</a></li>

          <li><a href="#">Contact</a></li>

          <li><a href="../about.php">About</a></li>

        </ul></td>

      </tr>

    </table>

  </div>

Sorry, i am new to this.

i have tryed this "http://www.plus2net.com/php_tutorial/php_login_logout.php" but i cant get it to work....