Are you talking about the mini 30mm ones? They are the biggest PAIN IN THE BUTT!! Here's a picture of the underside of mine. I find that they snap tighter if you don't line the entire the bottom (like the green one).
To attach the bow, you just glue it on, there's no other way (that I've found anyway). I don't use these ones very often and usually only attach little appliques to them.
Hope that helps!