In the Character Creation screen, use the Send to Game pop up. 

A Redemption Code will appear next to the QR code. If you want to, you can share this code with other players. 
Once the Redemption Code is generated, an icon will appear on the Characters’ thumbnails and this icon will be visible as long as the Redemption Code is available.

Keep in mind that each Character created will have its own unique Redemption Code so you may have up to 20 active codes. 

Each Redemption Code will be active for a week from creation. You can extend the active status by clicking on the Send to Game button. This can only be done while the Code is active and will extend the active status by a week.