This was such a hot topic over there I decided to help out and wrote a code for the entire profile page. We are going to start slow though since it can be as simple or as complicated as you want to get.
The simplest way to make a background (bg) is using a photo editing program, I use PSP.
Start with a new image 1440px X 900px. This is your average screen resolution. I'll post a link later to an explanation on hosting these images and grabbing their URL (location/address on the web) Right now let's just get the Bg made.
So now you have your blank 1440 x 900 image. You can fill it with any color/pattern/gradient you want.
Now lets create another new image 800px X 900px. you can also fill this with the color or gradient of your choice but I would keep it simple enough so people can read your profile information without getting a migraine.
Now that you have this, click on the edit button and choose copy.
Go back to your 1440x900 image and click on it. Now click on edit again, but this time choose paste as new layer. It should slap that baby right in the center so you have something that looks like this:
Now you are ready to host the image and get it's location.
For instructions on how to do this please
Click Here!
Ok, got the location?
Here is the code:
<*style>body{background-color: #000000 !important; background-image: url("PUT IMAGE DIRECT LINK HERE");background-attachment: fixed; background-repeat: repeat;background-position: center center; color: #ffffff}<*/style>
All you have to do now is remove the *s from in the <*brackets*>. I have to put them in there so the brackets show up.
The part that says color: is going to color your text. #ffffff is white.
Want a different color code?
Click Here to learn how to use a color pick tool.