How to implement a search box in c#

Hello:

I tried to implement a search box that can search either a text box.

I came across the "Search Box" thread on this forum, But I don't quite understand the code in that thread.

Here is the link:
http://social.msdn.microsoft.com/forums/en-US/csharpgeneral/thread/a07c453a-c5dd-40ed-8895-6615cc808d91

Can someone explain to me what sendMessage does and what is Cue property?

If I had a text box in the same form with the cueTextBox, How can I search a certain string through the text box.

Is there any existing algorithm for it?

Thanks