Although a whole book could be written about stock, stocks are actually really easy to make, and they add fantastic complexity to cooking.
Simply cover your bones and vegetables (in the form of a mirepoix, a mixture of celery, onion, and carrot in equal parts) with water, bring it to a simmer, and keep it at a very gentle simmer for at least 5 and up to as many as 24 hours, adding water as it reduces. You should be able to really smell and taste the meat, whether it’s beef, pork, lamb, poultry, or game.