How do I program the ons on my car with the garage door opener?

I have an 08 Mercury Milan and a Genie Promax PCG 450. I would like to program the visor ons to open the garage door so I don't have the use the remote. I had done it at one point however I turned the car off and the programming was undone. Please don't tell me to check the manual, there was nothing in the Milan's manual about these ons, and the maintenance staff for the property I live at does not know about the garage door opener.