If you are referring to 'Friends' log-in, I can't give you a full answer at the moment as I'm away & will be for a few weeks. You first need to have an email account that matches those available through the Friends system. GMail works for example. So if you have such an account you will already have a username and password. It's been close to 3 years since I've used Friends so without WSHR being open in front of me I can't advise further for now.
Any friends you have will then need to add you or vice versa to your friends circle within WireShare.