This is the basic way to prepare bone stock:
To make bone stock, start with 4 pounds of beef or pork bones (pork neck works really well). Pork bones will be more cooling, while beef will be a little warming. Bake the bones in the oven at 350 for 20-30 minutes. Then put the bones in your stock pot, add 1 gallon of water and 4 tablespoons of rice vinegar and bring to a boil. Cover and turn down to a simmer for around 8 hours. Strain the bones and let the stock cool. Refrigerate what you will use within a week and freeze the rest. As it cools it is normal for it to solidify into gelatin. This can be used for making congee, as the base for soups (diluted with water) or added in small amounts to soups, stir fry, steaming water for vegetables, cooking grains, etc.