Find pumpkin seeds by looting chests, trading with villagers, or harvesting wild pumpkins
Craft pumpkin seeds from one pumpkin in the crafting grid
Prepare farmland by hoeing dirt or grass near a water source
Plant the pumpkin seeds on the farmland
Leave at least one empty block next to each planted seed for the pumpkin to grow
Use torches or other light sources to keep the area lit
Wait for the pumpkin stem to mature
Harvest pumpkins when they appear on the empty adjacent blocks
Replant or expand the farm as needed
Use bone meal on the stem to speed up growth if desired