Uhhhh, what kind of watch would help us to help you! Pics of the case maybe, too.
Guessing it's something from the 60s? My Seamaster crystal ring snaps into place in a similar fashion. I had a moncoque Cosmic that was a bit more involved.
Can you post a photo of the top side of the bezel?
I have a number of Omegas with removable bezels and they use a plain compression crystal which is I suspect is what you need as well.