Before the revolution, Boston was a city under full control of the Templars, who managed to almost completely destroy local Assassin Guild. Your mission will be reconstructing the brotherhood and regain all the districts from your enemies. In order to begin, start with finding a district challenge icon on the map.
As you reach the designated spot, you will receive a short mission of killing a given soldier and saving oppressed citizen. Complete it and another marker will be placed on the map, pointing the person which you should contact. For now however he won't have much to tell.
Before receiving the mission of regaining the district, you will have to complete a few lesser tasks, similar to or identical as the one from which you begun. Unfortunately, they won't be marked on your map. In order to discover them, you will have to circle the area, searching for Templars harassing the citizens. Each completed mission will reduce the enemy faction's influence.
When the contact finally agrees to cooperate, complete the received mission to free the district from Templar reign. What are the benefits? Firstly, in regained districts you won't be bothered by Templars anymore, though British soldiers will still patrol them. Another benefit will be that you will receive a new recruit.
NOTICE! The first guild member can be recruited by completing Sequence 6 of the main story mode.