Open an anvil
Place the item you want to enchant in the first slot
Place the enchanted book in the second slot
Take the enchanted item from the result slot
Use an enchanting table to apply random enchantments to items
Use a grindstone to remove enchantments if needed
Combine compatible enchanted books in an anvil before applying them
Make sure the enchantment is compatible with the item
Use enough experience levels to complete the anvil action