Firstly, remove the battery. Next, you'll need to take out 7 screws (in red), 2 in the holes at the laptop corners and 5 in the battery enclosure.

Next, you'll need to unscrew 2 screws (in orange) in the hard drive cover, to the bottom left of the battery enclosure. These screws won't come all the way out of the panel, so when they won't come up anymore gently pull the panel off.