Understanding constraints in use case diagram

I've just read a book about UML and an currently trying to create a use case diagram of one simple domain.

The domain states:

There are two kinds of users: default and vip.
Default user can create no more than 10 posts.
Vip user has no restrictions.

What is the right way to bring this restriction into use case diagram? Is my diagram correct?

If it's correct, can I model the same way the next statement?

User can give only one star to post

Thanks a lot for your attention!

Solution

It's almost correct. You should write the text in curly brackets. That will identify it to be a constraint. Further you should use the correct case for Default User. Eventually you can link the constraint to the actor as well. And yes, you can go on like that. Maybe, Rate Post is another use case. Think about that.