You have been hired to protect a sacred town that monsters were trying to raid for a long time.You must protect the people who lives at this town.You only have armor,swords,and maybe a bow(if you craft it)Even though zombies are the only mob that attacks villagers,Other mobs may try to kill you.You must

1.protect villagers
2.light up the ENTIRE village(Helped you with some)
3.Plant potatoes,carrots,and seeds(wheat)in gaps in the dirt where the people of this town get their food(surrounded by tree logs)

There are also ranks which will have more info on the map

P.S.Even though the rules says no block breaking you may still break tall grass to get seeds