Get a garlic head from the grocery. Split it into the individual cloves (usually 6 to 8 in a head). In the Fall (around here the first week of November, probably earlier in Montana), plant each individual clove about an inch deep with the root side down. Cover them with about an inch or two of hay. In the Spring, they will grow up through the hay. In addition to leaves, they will form scapes, a central round shoot that will develop into flowers if you let them. Don't let them. Instead, cut them off and use them to make salad dressing and stir fries. Dig the garlic bulbs up in July and let them dry out. Keep a few heads to split into cloves and plant in the Fall for the next year. Eat the rest.
If you want to have better garlic, get the initial head from a mail order seed catalog. They are specially developed to be put in the ground for the next year's crop and they will produce bigger and better heads than the grocery store ones.