Here is the mobile app Groups screen. Let's choose a group with no contacts: Nursery 12. 

The Nursery 12 group screen opens. A confirmation message tells us that there are, indeed, no contacts in this group (orange box). No problem...we are going to change that right now. Click on Edit (green box).
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Although it says 'Edit', this screen is really for adding people to the group. At the moment, there are 0 Members, we are not adding/removing any (green box). 

We decide to search for people with 'dave' in their names and get one contact. 

Great! That's the person we were looking for. We select that contact (green box). Note how the information about the group has now changed (orange box).
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We want to look for more people to add, so we erase 'dave' from the search field.
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We decide to look for people with 'daniel' in their names and get a long list of possibilities.

The contact we need is at the top, so we choose him (green box). Note how the information about the group has now changed (orange box). 

We continue like this until we have added everyone we need. Then we click on NEXT to continue (upper, right-hand corner of the screen).
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