Hi! I'm writing this guide at 4:08 AM on a Saturday because many new users to Myspace are unfamiliar to CSS and its' inner workings.
Using this guide, you'll be banned for racism customizing your profile in no time!
First off: Most new users wanna set a background image; It's one of the simplest things to do.
To start, we'll lay down the most important part of CSS. The body tag. To understand why we need to do this. You need to know what "body" means. I'll make it quick.
An HTML document (what most webpages were, and still are, made of) contains 3 segments: the header, body, and the footer.
The header is for defining content that will be loaded before the rest of the webpage. It's where you can place a reference to a CSS document, or to load in an embed.
The body section is the most important, because it contains everything: all code, all objects of the webpage. It's all in the body. Every bit of web design that you'll ever do in HTML will be in this body section. It's oddly beautiful, in a way.
When you're designing CSS, any changes made to the body section will pretty much change the entire webpage, unless you account for it beforehand by placing some DIVs everywhere. But let's not get into that. What you need to know right now is that to make a background change, or to make the entire page shake and vibrate, you'll need to modify the body tag.
To make a background, you must do this: