This is the recipe that we've used in our family for a long time. It was passed down from my great-grandmother. You can use either navy beans or great northern beans, both work well (there was always a debate in the family about which one is better!).

Boston Baked Beans (note: I've converted some of the measurements to metric in case that would help)

1 pound (454 grams or 1/2 kilo) dried white beans
1 tsp baking soda
1/2 pound (225 grams or 1/4 kilo) salt pork, diced
1 tsp dry mustard
1/3 cup (75 ml) molasses (light or dark, depends on your taste)
3/4 cup (175 ml) tomato juice (or tomato puree)
1 medium onion, chopped
1 tsp salt
1/4 tsp pepper
1/3 cup (75 ml?) brown sugar (light or dark, depends on your taste)

Wash, clean and soak beans overnight. Rinse. Place in pot, cover with water and add baking soda. Boil for about 20 minutes until beans are tender. (Or, soak beans 2 hours in very hot water and boil for 1-2 hours). Scald salt pork. In a bean pot (oven proof, about 4-5 quart size), mix pork and remaining ingredients. Drain and rinse beans. Add to bean pot. Cover with boiling water. Bake, covered, at 250 for 6-8 hours. Add more water and stir as necessary. Note: all the seasoning amounts can be adjusted to suit your taste. For example, My family likes more brown sugar, less molasses, whereas my mom likes a lot of molasses.

Hope it comes out well for you!