HTML???? what the?

As you can see I am trying to customise my blog. I have made the header and it fits just right. I have made the background, but it wont fit just right. Its all about dimensions, and your computer screen might be a different size to mine and you need the right HTML code. I have gotten this far, thanks to my 17 year old son who will probably run a mile next time he see's me coming!

Its a work in progress bit I want it to look like this

the graphics I have used to make this and the header

are by Jofia Devoe, I have used her Summer Pleasures kit which is available at

http://www.afterfivedeigns.com/