Not as easy as between 2 UA flights.

All Air France arriving passengers are transported to the Customs/Immigration facility (IAB) in the main terminal. You go through Immigration (Passport Control) first; pick up checked bags from the carousel (there are free baggage carts there); head towards the exit where you surrender your blue Customs form.

Immediately after Customs there is a baggage re-check counter on your right. I don't think you can use it though - check the signs. If you can't use that re-check counter you will have to go upstairs to check-in at the Delta counter, which is almost directly above the Customs exit.

When you exit the Customs area, you are next to baggage carousel 14. Delta counter is up above that. Take the escalator just after carousel 13 up to the ticket counter level (there's an elevator behind the escalator). Check-in with Delta. Then follow the signs "To All Gates" which will take you down to the TSA security mezzanine. Following TSA security, down another level and take the train to the B Concourse for your Delta gate.