to put in a banner, you just make a picture that you like using an imaging program [like photoshop, but most computers have an imaging program that came with it or with a digital camera] then save it to an imagehosting server.... like photobucket. usually banners are much wider than they are tall, they are the images that you see over people's blogs [like the whole john mayer deal on mine]. then you insert the code into your custom header.
CODE
<!-- begin code provided by createblog.com -->
<img src=url of image here>
<!-- end code provided by createblog.com -->
[the url is like www.photobucket/yourmistake/lookmybanner.jpg or something like that... on photobucket you can just copy and paste the tag.] oh and btw, i love taking back sunday, hadn't heard that song in a while ;] good luck, let me know if you need some more help.