Hi Ruth,
1
Check the lens above the screen on your laptop, ensure it is clean and also if there is a privacy shutter on the lens, ensure it is open.
2
Ensure the lighting in your location is mainly in front of you, behind the screen, not behind you.
3
Open the Settings App.
Go to Bluetooth & Devices - Cameras - Integrated webcam
In there, you will find sliders for Brightness, Contrast, Sharpness and Saturation.
Try using those adjustments to improve the image generated by your webcam.
4
If that does not resolve the problem, those are the only settings available, the best option may be to go to the support page for your laptop on the manufacturers website to download and reinstall (not update) the version of webcam drivers and graphics drivers they provide.
If you have any difficulty locating that support page, click your Start Button, then just type msinfo and press Enter, please provide a screenshot of the resulting System Information window.