You can change the brightness on any Windows 10 PC in two main ways: through the Action Center, or through your Settings ...
If the default Windows mode is on Light, you can’t choose a custom color. This article explains how to change the color of the taskbar in Windows 10. How to Change the Taskbar Color in Windows 10 ...
You can change your Windows 10 login screen through your device's Settings app, and make it display any photo you like.