How to make a "screen region selector" to capture a region of the screen in .NET?

Question

I've used this http://www.vbforums.com/showthread.php?t=385497 sample to capture the screen and save it to an image, I'd like to know if someone have a sample for a "selector" for selecting the region of the screen to capture, like camstasia or camstudio have.

I dont want to understand how it works, just need a code sample but couldnt find any.