This page aggregates what we done and how it was done at Mitch Altman's workshop, so please read it first.
After Mitch explained some basics of electronics that I'll not write here we started soldering an Arduino with the Ladyada boarduino. With our working Arduino mounted on a solderless breadboard, we prototyped a TV-B-Gone using some resistances, a transistor, and a IR emitting LED. Parts list, schematics diagrams, etc can be found on the TV-B-Gone Workshop Page.
The design of the shield is work in progress, see TV-B-Gone shield on github, or a screenshoot of the PCB. It is designed using KiCad (Open source, `aptitude install kicad`) following this KiCad tutorial