Thanks Abhinav I figured out how to execute the toolbar button.
http://thebot.net/threads/vb-net-help-clicking-javascript-button.119250/
the code will be like this
Dim HTMLEles As HtmlElementCollection = WebBrowser1.Document.All
For Each btn As HtmlElement In HTMLEles
If btn.GetAttribute("src").Contains("images/obj16/tsearch.gif") Then
btn.InvokeMember("click")
End If