If you use iCalendar on your MacBook or have it imbedded on your website, here's how you can find the link to integrate the iCAL feed into your Church App:
Open the calendar on your computer:
Right click the calendar you want to integrate:
Set the calendar to Public and select Share Calendar:
Finally, take the URL and paste it into your new calendar media source.
If the calendar is on your website, right click the "get iCal link" under your calendar and select "copy link address", then paste that into your calendar media source.