Click the gear icon in the top left and make sure you are in the desired organization.
Under the top left gear icon, select "Organization Settings".
In the left-hand sidebar, pick "Integrations".
Scroll to the "API Clients" section.
Click "New API Client".
Give it a name, then click "Create API Client".
Copy and store the Client Secret safely — it won't be shown again.
Copy and store the Client ID — this one stays visible.
Click "Done".
You now have your Client ID and Client Secret. You can create additional secrets under a given API Client. The Organization ID, should you ever need one, is your Client ID minus everything after the "."
No. These are beta-level testing apps. You should not put any protected data through these apps.