After the sit through the credits (about 10-15 minutes) you will gain control of Connor again. You will see the mission icon pop up on your map. Here you must travel to three locations (Boston, New York and Connor's home village in the Frontier).
Easy achievement to obtain, as the missions are not really missions, they are just short interactive dialog between Connor and some other people he has ran into throughout his travels. If you are using the Fast Travel option, this should take less then 15 minutes to get.