New Look

I decided to change the look of my blog from warm colors to purples, whites and greys....I am really feeling those colors! So today I made a collage on Picnik and am now using it for my header but now I am getting frustrated because I can not figure out how to download a background image. I have a cute grey plaid background ( the same background that I use on my twitter profile) that I want to use but have NO idea how to get it to an HTML format. Anybody want to help a sista out??? It's driving me crazy!

Hope you all have a fabulous weekend!!!