Paste it into Gmail

1. Press Verify & copy above.
2. Gmail → Settings (gear, top right) → See all settings → General.
3. Scroll to Signature. Create one if you have none.
4. Click into the box and paste with Cmd/Ctrl+V.
5. Set it as your default for new mail and replies if you want it everywhere.
6. Save changes at the very bottom - it is easy to miss.