From the Contacts page you can manage your contact lists

1) Tap here to add a new contact list. Give it a name and choose if you want to send/receive proximity notifications to/from users that you are going to add in this contact list. You can change proximity options (radius and interval) in Settings page.
2) Tap here to view users added to this contact list.
3) Tap on the gear icon to access list's settings: from here you can change it's name and it's proximity options. You can also delete the list.