First make sure you have the latest version of Informant installed on your device by going to Informant settings>about. At present we are on version 5.01. Then Google syncs to Informant for Android automatically through the Google calendar that came with your device. There is no need to setup a separate sync to google calendar in Informant.
You should already see your Google calendar data populated into Informant. If not, please first make sure you have the Google calendar app installed on your device(s). You don't need to access it after this, it just needs to remain installed. Then tap the menu bars at the top right of your main calendar view in Informant and choose visible calendars. You should see your google calendar shown and checked to share data.
Now when you create your event in Informant, look at the top of the event entry to see where it's assigned to sync to. Tap this to choose your google calendar.