New User Wanting to Install More RAM

I have never done much maintenance work on my computer. I bought it last
year and have had very few problems with it, but i would like better
performance out of it in the gaming area.
I only have 1gig of ram installed and am using windows Vista Home
I have been told that this is not enough RAM and i can tell it by the
way the computer acts.
So i want to upgrade ram with at least 1 more gig if not to.
I have 4 slots and no idea how easy or difficult the process is.

1. Does the ram chip come with installation disk
2. Can i mess up my computer
3. Do i have to reinstall anything on my drive (I'm missing my dell
image file)
4. Anyone have a tutorial.

BTW i looked up my comp specs and found a great price of around 20-40
dollars for 2 1gig cards.
Thanks in advance