Begin by removing all 9 screws from the bottom of the laptop. These screws are safety screws so once they are loose, they wont fall out.

To remove bottom cover, pull up on the back of the cover to loosen snaps. Once they have become unsnapped, pull up on the right side and detach then the left side and detach. Once this is done, the lid should be able to pull off. Take care to pull it from around the ports.