i have not used it in a while, but there are a lot of tutorials out there.
Essentially as soon as hamachi opens, you have a "second network" with other hamachi users that have joined that network. And after that you also have to give them that hamachi IP-Adress if you are hosting the game.
Hello. Usually if some game hosting won't work it is because you, by default, don't allow requests from the internet through your router to your PC.
But before you tinker around with opening ports and stuff, which can be a security risk (!!!), try the programm "hamachi" from LogMeIn.
It basically is a programm that creates a virtual-privat-Network with the people you are inviting into your group on hamachi.
Just google it, install, create a group and then let your friends connect to the hamachi-vpn-IP (everyone gets a new, secondary, weird IP) :)
That should always work!
(i have not played and not tested this tho! But hamachi usually works)
