To add a header image, click on the Customize link when viewing your blog, then choose “Header Image” from the left navigation. Choose “Add new image,” then either upload an image or choose one from your media library. Most images should be long and narrow, but you can crop them as well.
Removing a header image
If you want to have remove one header image that is on your blog, click on the Customize link when viewing your blog, then choose “Header image” from the left navigation. Click o nthe “Hide Image” link in the “Current header” section.
Adding random header images
If you want to have a random selection of images to be featured on your blog’s headers, click on the Customize link when viewing your blog, then choose “Header image” from the left navigation. Upload additional images to be current headers by following the instructions above for adding a header image. As you add additional images, they should appear under the “Previously uploaded” section.
After you have uploaded all the random images you want to add as headers, choose the “Randomize uploaded headers” option below the “Current header” selection; if you want to remove one of the random headers, roll over a header image in the “Previously uploaded section,” and click on the “x” that appears over the image.