I have a session value and stored it in a text box.
and i want to change that value by a click.

<td height="30" valign="top" >&nbsp;</td>
<td valign="top"><input type="button" id="msg" name="msg" style="background:url(images/bg7.jpg) no-repeat; border: none; color:#FFFFFF; font-family:Arial, Helvetica, sans-serif; width:100px; height:35px;font-size:28px;" value="<?php echo $_SESSION['security_code'];?>" />

<td height="30" valign="top" ><small>Can't read the image?</small> </td>
<td valign="top">click <a href=''><small>here</small></a><small>to refresh</ small></td>

want in this click a new session value set in the textbox. or in any button click. can it be possible, if yes than pls let me know.