To add a new webcam to the program, click the "Add Camera" on the toolbar:
In new window choose the option "USB, built-in or other webcam":
Choose a webcam from the list. You can select a resolution too. It is recommended to apply as higher resolution, as bigger the monitoring area of the camera.
You can test a connection to camera here. To do that, click at button "Connect & Test".
If you can see the video in preview area, then click Next. Otherwise, make sure no other applications use your webcam at this moment.
On the next page, enter the name of your camera. A descriptive name (e.g. "Room"), can be helpful when using features where you need to tell your cameras apart.
Now you can configure your camera: