Click Vote Button

I'm trying to make it so when you click a button on my form it votes up for the specific item on the web page, i cannot figure out what code i should use i've tried
wb.Document.GetElementById("voteup").InvokeMember("click")
The code on the webpage is:
<li style="display: none;">
</li>
<li id="voteButtons1" class="voteButtons">
<a id="dislikeSiteU1" class="voteDown" title="Click to vote Down for this Result">Vote Down</a>
<a id="likeSiteU1" class="voteUp" title="Click to vote UP for this Result">Vote Up</a>
<input id="voteurl1" type="hidden" value="http://en.wikipedia.org/wiki/Home"/>
</li>
</ul>