How to Invite Members to Your LinkedIn Group
After you get your confirmation from LinkedIn that your new group has been created, your next step is to invite members to be a part of this group so that they can reap the benefits of group membership also. This is actually a multi-part process:
You have to define a list of pre-approved members of your group, which you upload to LinkedIn.
You should do this before you send out any invitations. Consider adding members to your list that will benefit the most from being a part of your group
You're allowed to e-mail your prospective members with an invitation to join your new group.
LinkedIn provides you with a web page that you can use to generate your invitations.
When someone clicks that link, LinkedIn checks to see whether that person is on your pre-approved list.
If so, she automatically becomes a member. If not, you (the group manager) see a member request in the Manage section of your group entry, which you have to manually approve so the person can officially join the group. The person's status shows up as Pending on her My Groups page until you approve her membership request.