In order to stream your desktop you will need a streaming software with screen capture capability.
Some recommended tools are:
- OBS Studio: https://obsproject.com/ (Windows + Mac, Free)
- Wirecast: https://www.telestream.net/wirecast/overview.htm
- ManyCam: https://manycam.com/ (Windows + Mac)
- Ecamm Live: https://www.ecamm.com/mac/ecammlive/ (Mac)
- SparkoCam: https://sparkosoft.com/sparkocam (Windows)
- CamTwist: http://camtwiststudio.com/ (Mac)
- NDI: https://www.newtek.com/ndi/tools/ (Windows)
As for NDI Tool, you will need both NDI Scan Converter and Virtual Input.