You are really not making a good first impression. Typing like you just did is probably harder then just typing normally!
There's really no step-by-step guide to make a gcp. You're going to just need to go around here and learn as much as you can about basic electronics, and as much as you can about gamecubes. Look at other people's completed portables and read their worklogs. They have a BUNCH of valuable information that'll help you avoid some pitfalls.
I'd also suggest that you start off with a simple project to get some soldering and basic electronics experience.
The bottom line is that there's no step-by-step, place the gooblygock in the dotted line on the board, kind of guide. You just have to learn enough about electronics and portables to make your own guide in your head.
Sorry, but if we held the hand of everyone coming into a complex project with no electronics knowledge, we wouldn't get anything done.
If after you've learned a bit about soldering and electronics, you have a more specific and useful question to ask, we will be MORE then happy to answer them to the best of our abilities.