disconnect battery

This is pretty generic, but i figured I would post the question here. I am brand new to cars. I have a 96 Saturn SL2. I just bought a cd player to put in the car, and the first line of the instructions is to disconnect the battery. So I opened up the hood, found the battery and its 2 connections. I tried to pull them off, but had no such luck.

You can all assume that I retarded, but how do I take the connections off, and does it matter the order (i.e. red or black first)?

Thank you.

you should need a wrench. AND YOU MUST DISCONNECT THE BLACK ONE FRIST!! the black is the ground, and the whole body is grounded. so if take the red one off first and you hit the body, it won't be pretty.

8mm wrench.