What is a one-sentence summary of the following article?
If you're on mobile, you'll need to tap the Facebook app to open Facebook. This is in the top right corner of your Group interface. On mobile, tap the "Add Members" option at the top of your screen. This will add them to your Group. Facebook presents your most frequently-contacted friends first; as you add these friends to your Group, the list will refresh with more friends.  You can also type the name of a friend you'd like to add into the "Add Members" field. On mobile, tap the name of each friend you'd like to add; this will select their name by placing a checkmark next to it. You can select as many friends as you like. There is no limit to the amount of members a group can have. On mobile, tap "Done" in the top right corner of this menu to add all selected friends to your Group. You can do this by clicking the "Members" tab at the top of your Group. You have successfully added members to your Group! On mobile, tap "Info" in the top right corner of your Group menu, then tap "Members". This will bring up a list of people currently enrolled in your Group.

Summary:
Open your Facebook Group. Click the "Add Members" field. Click the name of a friend you'd like to add. Add as many friends as you'd like. Review your Group's occupant list.