You could attend a Bay State Archer 3-d shoot, http://www.baystatearchers.com/bay_state_calendar.html

This group would be a good place to shoot 3-d targets and maybe learn by shooting with more experienced archers.

You could contact the Mass Bowhunters Association and ask for help.
http://www.massbowhunters.net/Contact.htm

But probably the best idea would be to buy a bag target from anywhere for cheap and head to the beach. How far are you from the public beach at Nahant? Almost nobody is on the beaches this time of year and setting up your bag target and shooting on the beach would be great hunting expierence with the wind, and finding a miss in the soft sand wouldn't be hard at all.

I know of 3 indoor leagues as well, Teepee Archery in Acton, Woburn Sportsmens Association in Bedford and Tyngsboro Rod and Gun in Tyngsboro.

That should get you started.