Here's how it works on iOS:
Tap on the blue dot and then tap on “Set as parking location” to add your parking spot to the map itself. Tap on the parking label on the map to open up your parking card and do things like share it with friends and view pictures of your parking area. This is in addition to the automatic parking detection you might have already noticed in Google Maps for iOS. If you connect to your car using USB audio or bluetooth, your parking spot will be automatically added to the map when you disconnect and exit the vehicle.
You can download Google Maps from the App Store for free.