In the Activity Feed, you can add another member to your team by clicking the add to team icon.

Additionally, wherever you see the add to team button, you can add another member to your team.

The 'add to team' button is also displayed on all profile pages:

When you add someone to your team, they will display alphabetically on your team page. 

Now that you have people on your team, you may want to follow their updates. To do this, you can either select ‘my team activity’ just above your team members, or you can visit the activity feed and filter by 'All Activity' or 'My Team Activity':

Desktop View of 'My Team Activity'

Mobile View of 'My Team Activity'