To invite users, go to the Community Members Space Tab – if you see the "Invite users" link you have permission to invite people to the community:
Clicking the link will take you to the invitation form:
Enter the user names that you want to invitation to be sent to. You can use the magnifying glass to search for users to add.
Enter a custom message that will be sent to the invited users.
Click the "Preview" button to see how your message will appear in the email and the users that it will be sent to. If any of the users entered are already members or invalid that will not show up on this screen.
Click the "Invite" button to confirm the invitation. If you are creating an invitation request (for Moderated or Closed communities) the invitation won't be sent until a community admin has approved it.
Click the "Cancel" button if you decide you don't want to send an invite.
You can display a link to the invite screen from elsewhere, using the invite-users macro.