This is a very basic overview of syncing data between Informant and a sync service.

First before you can sync your data you will need to determine where your data resides.
Please open your devices built in or stock calendar and reminders applications and see if your Informant data is visible there.

If it is then that means that your Informant is configured to use the iOS calendar and reminders database.  When configured this way none of the data is stored in Informant the device is simply sharing its database with Informant.  This also means that the device itself and not Informant is responsible for syncing the data.  The data will be synced based of the settings of your device itself.

If you cannot see your Informant data in the devices stock calendar and reminders apps this means that your data is in the Informant database and it can be synced via the supported Informant sync services.

The supported sync services are as follows

Google Calendar        Free         Calendar Events Syncing

Google Tasks             Free         Basic Task Syncing

Toodledo                    Free/Paid Task and Notes Syncing

Informant Sync          Paid          Syncs all Informant Elements

Evernote                    Free/Paid Notes Syncing

Once you have decided what sync service to use you will need to go online and create an account for the chosen service(s) if you haven't already done that.

The next steps are to go into the Informant app settings, sync accounts, and tap the add button and add an account that matches the account you set up online.  

Once you login tap the begin sync button.  Once the sync is completed on one device then you can go to the next device and sync it.

As long as your data is verified to be in Informant and not iOS data in Informant, and the sync accounts are the same in Informant on both devices that is all that is needed to sync.