Gridview - Update/Delete/Edit functionality (along with Add too)

I found the following link from msdn very useful in this case. This will explain you on how to do the edit/upate/delete functionality inside the gridview and add through a small form.

http://code.msdn.microsoft.com/Insert-Update-Delete-rows-b0a2d4e2/sourcecode?fileId=60725&pathId=665871416

Another video which is useful for learning about interfaces use is below:
http://tekpub.com/blogs/tekpub-free-bin/7964823-concepts-4-loose-design-with-interfaces