@jeff1, under the main menu where ‘Doors and Locks’ appears, just click on it, then click on the ‘settings’ icon at the top right corner (which looks like a gear). From there, click on ‘add a door’, enter a door name, specify the type of door (conventional, garage), press ‘next’, on the following page, press ‘know and control if the door is locked’; on the next page, select ‘connect a lock’, and choose your existing lock. After, if you want to be notified, just click ‘notify me when’ with the different notification options available. After, you click ‘next’ and then ‘done’.
You should be all set!
Regards.