How does cafepress.com work if you are selling?

You just upload a image to cafepress and they take care of the rest. There is a base price that has to be covered for printing/producing so ie 10 dollars for a shirt (im making these numbers up) and then you can decide to sell your shirts for 15 dollars. So for each shirt purchased you get 5 bucks.

You pay nothing ever. Nothing is ever produced unless purchased so you can upload as many designs as you want and then just sit around and wait/hope someone likes them and decides to buy them.

Actually, Cafepress controls how much you can mark something up. Also, they limit how much you get for a sale through their marketplace.

You might want to look at Zazzle.com. Also, you should read up about Print on Demand sites. Take a look at Squidoo.com.

And also http://www.envelop.eu