Step 1: Buy garlic from the supermarket, storing in your fridge. Either wait till it sprouts on its own or separate the cloves, wrapping in a damp paper towel and put in a cup in the fridge
Step 2: When the look sufficiently sprouted, plant in soil with the clove fully buried.
Step 3: Water on a regular basis. You know, regular gardener stuff.
Step 4: When the leaves on the garlic start to die, its probably time to harvest.
Step 5: Cure and store, or enjoy immediately.