Yes, you do need the wooden stamper to use with the stamps. As Susan explained above, there are grooves on the back of the rubber that lock into the grooves on the stamper.
If you want more information about JustRite products, I had a blog entry a couple of months ago explaining how they work and what I would recommend for newbies. Here it is:
http://uselesscrafts.blogspot.com/20...at-to-buy.html
If you have more questions, I'd be more than happy to help you.