1) use a link around the cancel button:
<a href="page.php"><input type="button" name="cancel" id="cancel" value="Cancel"></a>
2) put the link code right after the button code:
<input class="formButton" name="Clan_submit" type="image" id="Clan_submit" src="webassist/forms/fd_sharp_default/submit.gif" onclick="clearAllServerErrors('Clan_Sharp_Default' )" tabindex="12" /> <a href="welcomepage.php"><span>CANCEL</span></a>
rather than outside the LI tag that contains the button