Help me to modify this code and to (more importantly) to understand how...

Hello- we have a small PHP/MySQL forum.  I have installed some 3rd party code (hack) that shows a list of users who have visited the forum in the last day.  When you hover your mouse over one of the visitors names, it displays a tiny pop-up that shows the time that the user was active.  For example, I just hovered over my name and the window said 4:55 PM.  Very cool.

The code as it is, is shown below.  Here is what I hope someone can help me with.
1.) I would like to know what part of it actually triggers the little pop-up window to fire with the time.
2.) I would like to know how I could add the date to the pop-up window.  So in the case of my example above, it would then say 10/24/2006 4:55 PM instead of just 4:55 PM.

The reason for number 2 is that I would like to implement this code in another area of the forum where the date will be necessary.  THANKS for any help.  I am very new to PHP- though I am eager to dive in!

The code:
-----Start------

if ($show['wvt'])
{
      if ($vbulletin->options['wvt24'])
      {
            $cutoff = TIMENOW - 86400;
            $whodesc = $vbphrase['visited_today_24'];
      }
      else
      {
            $whodesc = $vbphrase['visited_today'];
            $tnow = date('YmdHis',TIMENOW - intval($vbulletin->options['hourdiff']));
            $cutoff = TIMENOW - (substr($tnow,8,2)*3600 + substr($tnow,10,2)*60 + substr($tnow,12,2));
      }

      $todaysusers = $vbulletin->db->query_read("
            SELECT userid, lastactivity, options, username, user.usergroupid, displaygroupid,
            groupa.opentag as opentaga, groupa.closetag as closetaga,
            groupb.opentag as opentagb, groupb.closetag as closetagb
            FROM " . TABLE_PREFIX . "user as user
            LEFT JOIN " . TABLE_PREFIX . "usergroup as groupa ON(user.usergroupid = groupa.usergroupid)
            LEFT JOIN " . TABLE_PREFIX . "usergroup as groupb ON(user.displaygroupid = groupb.usergroupid)
            WHERE lastactivity > " .$cutoff. " ORDER BY username
      ");
            
      $totaltoday = 0;
      unset ($whotoday);
      while ($today = $vbulletin->db->fetch_array($todaysusers))
      {
            $totaltoday += 1;
            if ($vbulletin->options['wvtnames'])
            {
                  $today['opentag'] = $today['opentaga'] ;
                  $today['closetag'] = $today['closetaga'] ;
                  if ($today['displaygroupid'])
                  {
                        $today['opentag'] = $today['opentagb'] ;
                        $today['closetag'] = $today['closetagb'] ;
                  }
                  $today[visible] = 1 ;
                  if ($today['options'] & $vbulletin->bf_misc_useroptions['invisible'])
                  {
                        $today['visible'] = 0 ;
                        if (($vbulletin->userinfo['permissions']['genericpermissions']
                        & $vbulletin->bf_ugp_genericpermissions['canseehidden'])
                        OR $today['userid'] == $vbulletin->userinfo['userid'])
                        {
                              $today['visible'] = 2 ;
                        }
                  }
                  if ($today['visible'])
                  {
                        $wrdate = vbdate($vbulletin->options['timeformat'], $today['lastactivity']);
                        $whotoday .= "<a rel=\"nofollow\" href='member.php?u=$today[userid]' title='$wrdate' >";
                        if ($today['visible'] == 2)
                        {
                              $whotoday .= $today['opentag'].$today['username'].$today['closetag']."</a>*, ";
                        }
                        else
                        {
                              $whotoday .= $today['opentag'].$today['username'].$today['closetag']."</a>, ";
                        }
                  }
            }
      }

      if ($whotoday)
      {
            $whotoday = substr($whotoday, 0, strlen($whotoday)-2);
      }
      else
      {
            $whotoday = $vbphrase['no_visitors'];
      }

      if (!$vbulletin->options['wvtnames'])
      {
            $whotoday = $vbphrase['no_visitors_display'];
      }

      if ($vbulletin->options['wvtcol'])
      {
            $show['wvt1']= '<a style="float:'.$stylevar[right].'" href="#top" onclick="return toggle_collapse(\'forumhome_todayusers\')"><img id="collapseimg_forumhome_todayusers" src="'.$stylevar[imgdir_button].'/collapse_thead_collapsed.gif" alt="" border="0" /></a>';
            $show['wvt2']= '<tbody id="collapseobj_forumhome_todayusers" style="display:none;">';
      }
      else
      {
            $show['wvt1']= '<a style="float:'.$stylevar[right].'" href="#top" onclick="return toggle_collapse(\'forumhome_todayusers\')"><img id="collapseimg_forumhome_todayusers" src="'.$stylevar[imgdir_button].'/collapse_thead'.$vbcollapse[collapseimg_forumhome_todayusers].'.gif" alt="" border="0" /></a>';
            $show['wvt2']= '<tbody id="collapseobj_forumhome_todayusers" style="'.$vbcollapse[collapseobj_forumhome_todayusers].'">';
      }

      $ftotaltoday = vb_number_format($totaltoday);
      $search_text = '<!-- end logged-in users -->';
      $vbulletin->templatecache['FORUMHOME'] = str_replace($search_text,
      $search_text.fetch_template('Display_Visitors'),$vbulletin->templatecache['FORUMHOME']);
}

-----End-----