"So we know who and what this file is for, please enter your name: and email address: and the product you'd like this image imprinted on:"

I suppose you upload the file first and use the same email and name so they can match the file with the order.

After that, go back to the brag tag page and leave the price blank. I think the "Add name" is what you want it to say (like how mine says "woof!").

Click on Checkout

Enter your address and such

Click on Submit

Click on "free brag tag"

If you're still confused, you could always go here and ask them.