I am also very new to the website building but you can try the following. In the members area click on Website Hosting, then Account manager, then on Upload Tool, a Java Applet opens which allows you to upload and download files to and from your web site. I then guess that the files will then be available for use when you use your wizard to edit your pages. Click image to choose and image for the page being edited.
I hope this helps.
you could also put the picture you want in *my pictures* and when editing your site, click upload picture and browse in my pictures and upload the 1 you want, hope i helped