You will need to get a manual that shows you where all the screws are. None are usually under any keys, you usually take the screws on the bottom off first, then that will loosen the keyboard allowing you to take that off and gain access the the screws under the keyboard.
If you haven't done it before you will have to google a guide to do so. Usually unscrew the bottom screws, which will loosen the keyboard, which will give you access to one or two screws that hold in the DVD drive.