I would start with a brooder and a heat source only if they seem to be huddling. You can then put them outside in about a week. You can put them directly into the coop but I would may be set them up in the main coop area for a couple of days with a light. The ramp looks like it may be a bit high for them to walk up and down. Make sure they have medicated starter if they where not vaccinated for about two weeks and add sav-a-chick to there water for the first week to help with travel stress.