At the bottom of the cartridge is the set of seals. Remove any mineral sediment that has built up in this area. Reassemble the faucet reversing the order it was taken apart. When you raise the handle of this faucet, the stem also raises, controlling the flow of water. Rotating the handle to the right or left controls the water temperature.
Leaks usually mean replacing the o-rings or the entire cartridge.
If this is the case, unscrew the retainer nut, then lift off the spout. This clip is what holds the cartridge in place. Use long-nose pliers or a screwdriver to remove the clip from its slot. If the 0 rings are worn, install new ones. When the cartridge is replaced, they should be in exactly the same position as when removed.