1) Sign into your admin dashboard
2) Go to the Members tab
3) Click "Add custom fields"
4) Click "Add a custom field" and create as many new custom fields as you'd like.
Selecting an icon will display that icon beside the field on the Members tab in the app. "Required" fields must be completed by new members when entering the app for the first time.
5) "Save all changes" and you're good to go! (You'll need to force-quit your app to see the change reflected in the app.)