Using Paint, Photoshop, Picasa, or any other type of artistic software you would like, create your desired graphic. When you are ready to get them onto the internet, upload them via Tinypic or Photobucket.
Any image manipulation program can be used to create graphics for your Myspace page. Just create a picture and make sure it is a correct size. There are probably a guide online on what should be what size. The just upload it to your picture or upload it to a picture hosting site and code it into your page.
It is not possible to upload pictures/graphics directly to MySpace. You only can link to a picture in the internet. You have to upload the picture to flickr or imageshack.
The easiest way to do this is to use an automatic generator from an external website. You can select one of these websites and brows their categories. Once you find a layout that you like you will be given an HTML code to insert into the HTML editing page in your myspace account. Just copy and paste.