Ram is the same as Memory for your computer.
here's some explanations that are better than I could give-
http://ezinearticles.com/?How-RAM-Af...-RAM&id=832188

http://computermemoryupgrade.mysuperpc.com/

and some videos on how ram is installed-
http://video.google.com/videosearch?...8&sa=N&tab=iv#

It's pretty simple really - but if computer is under warranty opening the case could void that. You probably would need a approved tech person to do the job in that instance. But I'm not sure since I build my own so I'm the warranty person LOL.

You can see the amount of Ram you have by right clicking on "My Computer" and a pop up will come up with the General page.
in the lower part it should have Computer
and show the processor type , Ghz and MB or GB of RAM .

I did run with 512 for many yrs but just upped my ram last fall to 1.5GB