Building a SIMPLE computer device

Ok

I want to build a simple USB computer device. I looked at..

http://www.delcom-eng.com/downloads/USBPRGMNL.pdf

and did some programming for it. But now I want to take it a step forward.

I want to make a mouse, or even a one button keyboard! using USB.

Does anyone know any sites or tutorials or anything that takes a newb through the steps with wiring, hooking up the USB cord to what ect.?

As in. You goto radio shack, buy some parts, wire it, then program the drivers...?

Is keyboard more complex then I think it is?

Thankyou for all input!