Find grass blocks in plains, villages, or other grassy biomes
Break tall grass to get wheat seeds
Till dirt or grass with a hoe to make farmland
Plant the wheat seeds on the farmland
Place water nearby to hydrate the farmland
Wait for the wheat to grow through all stages
Harvest the fully grown wheat to get wheat
Find wheat in village chests
Find wheat in shipwreck chests
Find wheat in mineshaft chests
Trade with farmer villagers for wheat
Use bone meal on planted seeds to speed up growth