If you want to use your MacBook's built-in camera, you first need to activate it. Here's how:
1. Open the Camera app. You can find this in the Applications folder or by searching for it in Spotlight.
2. Click the Camera menu in the top bar and select Show Video Settings.
3. In the new window that appears, select Built-in iSight from the Camera drop-down menu.
4. Your MacBook's camera should now be activated and ready to use!