Baby Sleep

Baby is 2 months plus.. he usually falls asleep when being carried or when being swinged in the cradle.. when i put him down on the bed after dozing off on my arms he opens eyes and i have to put him back to slp again by carrying him.. baby dosent sleep on baby cot or on mattress.. Any advice on how i can train bby to slp on baby cot/mattress/ co- slp with parents..