Configuring Pushover notifications in Oh Dear!
Once you're in the notifications menu, you can see the Pushover configuration settings.
You'll need an API token and user key, which you can get by registering an application at Pushover.
Once you have your API token & user key, you can add them in the Oh Dear! notifications screen.
For more details on creating your Pushover application to get the API token & user key, check out the official Pushover documentation.