1. Open the Dashboard from the status menu or by showing the Camera

2. Click “Share” to share your Desktop

If you have more than one monitor

Click the triangle on the right of the Share button, navigate to Displays and choose your preferred desktop.

This desktop will automatically be used whenever you click the Share button.

You can also set your preferred desktop via the top menu: Present → Shared Desktop → [...]

See also: How to share your desktop from a Stream Deck