This is far more difficult than it sounds. HTC hasn't released the source for ICS, so no one has been able to build a 100% working kernel for AOSP. And those guys have been playing with it since January for the Evo 3D. If you want to learn how to develop ROMs, I would recommend you mess with the stock Sense ROM, first. Although I'm not a dev, either, so I can't honestly say that's the best path or not.