Yea, I honestly doubt that the components in your computer will be able to put up with much overclocking at all.
Since you don't seem to know too much, the basic issue with overclocking is heat. We could theoretically run all computers at 3423748623 Ghz, if we could cool them off sufficiently. Similarly to the way the Bugatti Veyron needs 10 radiators to run at 253 mph, you need a lot of cooling power when you overclock. You could overclock slightly, but that wouldn't get you much of a performance boost, and wouldn't be worth it. You could try overclocking a decent bit, but you're almost surely going to need an after-market cooler, or at least decent cooling and airflow in that PC to begin with (which I'm certain is not the case.)
Also, the components in the computer have to be able to handle the increase without crapping out. You can't take a Honda Civic engine and just put 4 turbos on it - you'll blow it apart. The processor would be fine, but your RAM would probably be the limiting factor. It would start generating errors as you pushed it harder.
If you really want to take a stab at it, there are some very useful guides online (for example, the overclocking forum at Tom's Hardware:
http://www.tomshardware.com/forum/forum-29.html). It's not TERRIBLY complicated if you understand what's going on, but there is a decent amount of stuff you need to know first.
Bottom line: I really don't think it would be worth the trouble on your particular system. If you really need better FPS, consider a physical upgrade