Tony,

I am assuming you are talking about Remote Assistance as opposed to
Remote Desktop because you used the word invitation. The invitation
that gets sent to you is sent through email contains an attachment
named RAInvitation.msrcincident. Open this attachment and you will get
a prompt asking for the invitation's password (provided there was one
specified) and then it will try to connect.

Keep in mind that there are other issues involved if you are dealing
with routers/etc. Read up on the other posts for more information
about those.

-Gary Hibbard