Since you haven't given us any real information to help you, I can only assume you mean the images associated with the Website Wizard themes. The Website Wizard is self contained and very restricted. The images are managed from the CSS file and the Wizard does not give you access to that file.
If you don't like the restrictions of the Wizard and want to move forward, you should get a web page design application on your local PC and create your pages there. Try some of the following links: