I do mine the same way that charles p does his, except I use a paper bag. to start onions from seed you have to start early, around the same time you would start celery in your area, I keep them under flourescent lights (cool white) for 18 hours a day, and keep the tops cut back to around 6 inches.
For green onions I just start with sets on my deck, any good sized container will do, I like old coolers with the lid removed, and drainage holes drilled in the bottom. The trick is to plant them as close as possible in the container, for maximum production. Onions are heavy feeder so I'll give them a shot of miracle grow every two weeks or so.
Once they start geting ahead of me I'll start freezing them in containers, bulbs, stems and leaves in seperate containers cause the cooking times are different, freeze the bulbs in water or chickenstock, or the outer leaves will harden up on you, and come winter in soups they can't be beat!..............steg