Get and apply the book
Mending does not drop on the enchanting table. Look for a book in mining, fishing, or from a librarian. Conditions are different for regular trading and experimental villager rebalancing: check your world settings before searching for a specific trader. Reference: Minecraft Reference: enchantments.
Place the tool on the left in the anvil, the book on the right; check price and summary tip. Enchantment has one normal level. On a bow, Mending is incompatible with Infinity.
Leave the item being repaired as the only candidate
In Java, it is convenient to hold the pickaxe in the second hand, and gain experience with the first. In Bedrock, most tools are not placed in the second hand: keep the pickaxe in your main hand when picking up orbs. Armor and elytra must be worn.
Remove other damaged equipment from Mending. It can receive part of the spheres instead of a pickaxe. There is nothing to repair things that are completely serviceable, but for diagnostics it is easier to remove the unnecessary things altogether.
The purpose of the profession and the replenishment of transactions are discussed here: Villager trading: professions, books and restocking.
Find more XP
Spheres from combat, trade, ore and the issuance of experience from the furnace work. Mining earth or ore with Silk does not create the required flow. In Java, one point of experience restores up to two points of durability.
For the furnace: prepare a batch, stand nearby, pick up the tool being repaired and manually collect the result. Keep an eye on your durability bar. If experience has appeared, but there is no repair, check your hand and competing equipment; if there are no spheres, the source of experience. Don’t expect a breakdown: Mending will not return a missing item.
A practical example of feeding into different furnace slots is shown here: A compact auto smelter with three hoppers.
