Here are the posts pertaining to: Images
This is where we will be dealing with the Wordpress Media Library, which is where all your images, audio and documents will reside. Because images are an important part of any website we will be going in depth on how to use images within wordpress.
There are two basic ways to add a background image into the WordPress default Twenty Eleven theme. One is have a full page background the other is to have a small image, usually a pattern that will ’tile’ across the page.
Full page background
The full page background image is simple in concept. I guesstimated, based upon the header dimensions, that a picture of 1400 pixels would fill the browser window. The key to using a large image is optimization. Optimization is the method of making a picture file small enough to load quickly while keeping the picture itself large and of good viewing quality.