A backup is very important. We recommend that you never send coins to the device before you have made a backup. A backup should be made once and should be kept in a safe place. It gives you access to your tokens even if the device breaks down.
Click on your computer to 'Create a backup in 3 minutes'. Read the text and confirm that you understand how to save the backup. Click on 'Continue'.
Your Trezor will now show 24 words. Write these correctly and in the right order on the supplied paper. Then press and hold the green button to confirm.
The Trezor now asks you to check all words one more time and to check them correctly.