How do I get my 4 month old crib or bassinet trained?

From birth, my parents have spoiled my son by letting him sleep in their arms. Now he will not go to sleep anywhere else but in someone’s arms. He will sleep in his bassinet for 15 minutes and wake up screaming. The only place besides our arms that he sleeps is on our recliner. Forcing me to sleep on the couch. I haven’t slept in my bed in 4 months. Please help!