Hi
If this is a USB webcam, please connect it directly to the laptop, then open Start, type Camera, and open the Camera app. Allow camera access if prompted.
If you see the laptop’s built-in camera instead, click the “Change camera” icon at the top right to switch to the external camera.
Microsoft’s guide:
https://support.microsoft.com/en-us/windows/hardware/camera/how-to-use-the-windows-camera-app
If it still does not work, please share the camera’s make and model, whether it connects by USB or HDMI, and what the Camera app shows: a black screen, the built-in camera, or an error message. Please also confirm whether you are using Windows 10 or Windows 11.