Hi Lauraine, hope this will help you. Here is the information on invitations:
Just as an aside, I found when I did this that the Wiki email was sometimes hitting the junk mail under regular emails. I sent a "regular" email, with an explanation about Wiki, what I was doing, etc., and provided a link to the main page. I let them know they would be receiving a "wiki" email from me "inviting them" and to let me know if they did not receive. If you have a common relative they would be interested in, you could send a link for that page so they could view/link to ancestors.