My chickens wont survive.

My father recently bought about one dozen baby chicks we had them warm and indoors for a couple of days. Once they were
put into the chicken coup they all died. what could have been the reason? I live in a tropical climate (Trinidad and Tobago)
so its never really cold even at night. The coup is about 15 feet from my house. I cant seem to understand why my chicks died.
Recently as well, two of my older chickens died.

I keep my baby chicks separated for at least 6 weeks, often 8. They need to be kept really warm for the first weeks at least. Also, if I put chicks in with the adults, the adult chickens kill them.

I think i put them in too soon. thanks for the advice im new to this.

I use a heat lamp for my chicks and make sure they have a spot that is at least 90 degrees for the first week, 85 for the next, 80 for the next, etc. Once they are fully feathered they can go without extra heat, but I keep mine from the adult chickens until they are full size when I can. I have a separate little pen with a doghouse in it for them to live in until they are adult-sized and can get away from the older chickens. I also have places in the big chicken run that they can hide in if they want to, as well as several big trees, bushes, etc.

Wow that info was very helpful now I know what should be done thanks so much @todd

Todd covered it perfectly. Follow his suggestions and you will do fine next time.

If you don't like or don't want to use a heating lamp you can use a heating pad:
http://www.backyardchickens.com/t/1088644/mama-heating-pad

Be sure to use a heating pad that doesn't shut off every two hours.