I did a quick overview of how to install OBS here. If you’d like to add a webcam to that install then here’s how you do it…
- Click on the “+” in the “Sources” area.

2. Select “Video Capture Device”

3. In the “Create new” textbox enter “Webcam” (or whatever you want to call it) and click “OK”

4. Select the Webcam or capture device you want to use and press the “OK” button. In my case my webcam showed up as “USB Video Device”

5. The webcam will now show in the main view. You can drag and re-size it if required.

That’s the lot. Hope it helped!