When you're looking at the page of the product you want to use as the thumbnail, click the "Link" link and you can right click and save the picture, then upload it back to your Image set. You can do that with your own images - it's no different than posting the links on various websites/blogs - that's what they're there for - as long as it's on or to bring people to your Zazzle store.

Then, go to your Account area and the Products tab, and select the category you want to use the image for. Under the title of the category (next to the grey folder), click the "Edit" link. You'll see a link to "Change" the image. Select the product pic you uploaded (or you can upload it at this point from your computer), and save it.

Hope that answers your question.

Patricia
PR Prints