1. Click on "Account Settings" in the top-right
2. Click on "Integrations" in the left-hand sidebar
3. Click on the "Mobile Apps" card in the list
4. Create a new mobile app, name it, and remember the "short identifier". This will be used as the "app_id" later.
5. (Optional) install any necessary APNs keys or GCM keys that you need for push notifications. Note: Push notifications will not work unless you install keys here.