On a Mac:
Click the "Apple" logo in top left corner of your screen
Select "About This Mac."
On a PC:
Go to "Settings"
Click on “System"
Click on “About"
Once you find the serial number:
Type the serial number into the "Add item" information form in your account.
When you take a photo of the "About page"
Take a clear photo showing the entire screen and keyboard of your laptop
Make sure the screen is powered on with the about page/system showing
Then take a photo of the back/bottom of your laptop.