Change the look of chat help

Hi all,

http://battlefield360.forumotion.co.uk

Phbb2

I am very new at all this css code stuff and im struggling a bit. My query is related to my chat and i want to change some stuff on it. I have seen the tutorial which is great but cant seem to get my head around it.

how to paste them into the css sheet. When i put a code in nothing happens? Should i be pasting them in one after the other? should there be spaces ? and should i be putting something in the code as well. It seems really simple but i am having trouble.

here is my boring chat box



I want to change the background and styles of it. I want a pic as the main background

I have edited this 4 times in the hope to simplify it if no one can help on here do you know of any one that can help me with this.