I am going to have to assume some things in order to get to the heart of the project at hand.
1. You can read.
2. You can browse wiki.laptop.org.
Assuming 1. and 2., you should be able to go to http://wiki.laptop.org/go/Disassembly
and read the detailed and complete instructions on taking apart your XO. For Phase I of this project, you don't need to take the top half of your XO apart, just the keyboard part. When you're done getting everything apart, you'll have an XO "head" dangling two cables. The head will still works on AC power, as shown in the first photo, but the bottom part pretty much does nothing at this point.
Here I am making sure that the keyboard works. I forgot to do that before I voided its warranty, but luckily it has no problems.