Find at least 2 adult villagers
Make sure they are not nitwits or babies
Give them enough beds
Make sure each bed has at least 2 air blocks above it
Give them enough food
Use bread, carrots, potatoes, or beetroot
Drop food near them or trade with them
Keep them safe from zombies and other mobs
Wait for heart particles
Let them breed and create a baby villager
Repeat with more beds and food for more villagers