RAM is fairly easy to install, but usually it's slightly more difficult on a laptop. It comes on a card (usually referred to as a module), and you install it yourself (or get a friend to install it if you're not comfortable). You should go to the apple support pages and seach for "installing memory", find the model of computer you have, and check out the installation procedure. They have quicktime movies available in some cases that will walk you through the procedure.
Then you'll be able to determine if it's something you'll be comfortable doing. (It really is easy, but I was pretty hesitant the first time I installed RAM too.)