Upgrading RAM is one of the easiest installs to make, so it's a great step for someone who's never messed around with the internals. As long as you get the right parts and install them properly, you're good to go, even easier than a hard drive install. So I'd say give it a shot.
The best way to find out what your system can support is to go to a site like newegg or crucial and use their lookup tool. If you go to Crucial.com it's right on the main page. It'll even point you to exactly what products work in your system.
I believe they have installation guides there too but installation is pretty easy. Once you have your case open, just look for the memory modules. There are two plastic clamps on each, on the ends, that you snap open, and the module should lift right out. Put in the new ones (they're impossible to install incorrectly, there is a notch on the module that lines up with a spot on the slot you install them in), and snap the clamps back in place. Restart your computer, check to make sure it recognizes the new memory, and you're done.
Just make sure you work in a clean, comfortable environment, and ground yourself on something metal before touching the internals (static electricity from even walking on carpets is unlikely to but can cause problems). While you're in there, you might want to invest in a can of compressed air and clean out all the dust, too.
Good luck. I'd suggest just upgrading to the max you possibly can, which I'm gonna guess is 1GB. But look up your system on crucial and tell us what it says about it. Or just post the model number.