Shoutbox

Thats not how you invite people to GMail.
On you main GMail screen, the one with your inbox. Underneath the filters on the left side of the screen. If you have invites there will be a thing that looks abit like this
Invite X friends
to Gmail
And X being the amount on invites you have.
However this wont be there is you dont have any invites.

Also please dont double post, just edit your first post