When you've added a contact to your Contacts Module, you can then invite that person to register with your group.
Looking at your 'unregistered' contact (below):
Click anywhere along the person's name to open up their page (below):
Over on the right side of the page (see above), click on the blue button "Invite Contact" - the following pop up screen will appear:
In the above invite - the name of the logged in administrator will be also be on the message (In this case: Nathan Flood). There is also the option to add some text in the box below the "Register or login in now" link. All the other text is set in the system and cannot be edited.
Click on the blue "Submit" button on the bottom right side of the pop up screen and the invitation will be sent.
Back on the person's contact page - you will see an Invitation Link with expiry date (see below):
This link will be available for the person to use until 5th October - after that time, if they haven't joined up but would like to, you can repeat the invitation process and a new link (with new expiry date) will be issued.
When the invitation has been sent - the system will show the date and status of the person as follows:
When the Registration process has been completed by the person - the status will be updated to "Yes" for Registered (below):
The symbol to the far right of the record - shows that the person has registered using their email + password (if you move your mouse over the symbol in your live data - it will show the email address the person used to register). Forgotten passwords can be reset on the sign in page, using the link there.
Other symbols that could appear here are: Facebook, Google+ and Microsoft. The person will need to use the same log in method each time they access their account.