The RAM is behind a panel in the battery compartment, you need to remove 3 small Phillips screws and pull out an "L" shaped piece of metal.
When you install the RAM you must push it into the socket quite firmly. There is an initial "thunk" which you may think means it is finished -- it's not. You have to get both thumbs on the RAM and push it in another 2mm (1/8") to seat it all the way into the socket.