@ Lia, yes, as long as you have Hamachi online, invite your opponent to call into your network (by entering network name/network password in their hamachi) and then they can call you on that IP number.
So say your hamachi network is called Rainbowgym and your password is Rainbowgym, your opponent needs to login to your network by entering those data in their hamachi, and then you can play on your created Hamachi IP.
@ Anna, Hamachi should be working independent of router, cause your in fact creating your own personal network. Portforwarding is the kind of thing which is router dependent.