Also I should mention that when you installed myCal iOS would have asked for permission to access your contacts. That was for this exact kind of feature, myCal will display any contact dates it finds with an appropriate 'age' type number.
If you said no to the iOS request, this can be changed by doing the following:
- Go into the Settings app (not settings in myCal)
- Tap Privacy, then Contacts
- Set myCal PRO to ON
Regards
John