You can select your own banner through this menu.
Here you see the active uploaded banner.
Through the selection menu, you can select a banner.gif on your local machine to be uploaded to your site and replace the one stored. First browse for the desired banner.gif in one of your directories, then click on "Upload".
You can create your own banner on your local machine through various programs (photoshop, etc.), but remember to name your banner file: banner.gif.
In the menu, you will also see suggested banner parameters for your banner, which fit the selected template best, but of course you are free to make a choice of your own.

When you change template, the standard setting will be the Flash Banner associated with the template.