Hi, I will assist,I'm sorry about the issue. After removing the lens cap on the back of the garage-door opener's power head unit (not the remote key), you should see the Locate the "Learn Code" button in the bottom right-hand corner at the front of the power head.
For full details; please see page 23 to 25 on the manual at the website below:http://nationaldoor.net/uploads/files/Openers/Genie%20ProMax-Stealth%20Manual.pdf
More info if needed:
Please let me know if there is any issue. Thank you