How to select from drop down list. C# webbrowser

<ul class="ui-autocomplete ui-menu ui-widget ui-widget-content ui-corner-all" id="ui-id-34" tabindex="0" style="z-index: 1; display: none;"></ul>

<li class="ui-menu-item" role="presentation"><a id="ui-id-128" class="ui-corner-all" tabindex="-1"><b class="yl">Html</b></a></li>
<li class="ui-menu-item" role="presentation"><a id="ui-id-129" class="ui-corner-all" tabindex="-1"><b class="yl">css</b></a></li>t;css</b></a></li>
<li class="ui-menu-item" role="presentation"><a id="ui-id-130" class="ui-corner-all" tabindex="-1"><b class="yl">xml</b></a></li>t;css</b></a></li>
<li class="ui-menu-item" role="presentation"><a id="ui-id-131" class="ui-corner-all" tabindex="-1"><b class="yl">js</b></a></li>

how to selected on webbrowser. i don't have any idea. Can you help me