Where do I set up referential integrity?

I just bought the xpert edition. I am trying to find the settings for keys and referential integrity. I can’t for the life of me find it. I thought it would be available by double clicking the lines in the database diagram like other programs.

Any help appreciated.
Thanks.

ok, i see how to do it in the constraints tab now. Never seen it there in other programs. I know FK is a constraint, but you can usually do that stuff in the diagram area.