The piece of code you are looking for is:
Invoke a method in the DOM-Element
// The WebBrowser control
System.Windows.Forms.WebBrowser webBrowser;
// Perform a click on an element
HtmlDocument document = webBrowser.Document;
document.GetElementById("id_of_element").InvokeMember("Click");
The code above performs the click in the WebBrowser Control for you.
Assign an event handler
If you want to assign an event handler:
document.GetElementById("id_of_element").Click
+= new HtmlElementEventHandler(el_Click);
with:
void el_Click(object sender, HtmlElementEventArgs e)
{
// Do something
}