NEW INSTALLATION:
After downloading, open the installer and follow instructions to create a bootable USB drive or an ISO file to burn to DVD. Please make sure to back up your important files and data before proceeding! Once you boot your PC / Laptop with the DVD / USB drive, the installation program will run. Follow the guided steps of the program to set it up to your preferences and complete the installation.
During the installation you will be prompted to enter the license key you received by email. In case you don’t have the key on hand, you may choose the option “I don’t have a product key” and enter the key after finishing the installation.

In case you didn’t enter the license key during installation:
After installing the Operating System, right-click on This PC in the file explorer and select the Properties option. Click on Product Key and Activation. Go to Change product key to enter the key you received by email. Your copy of Windows is now activated.