Super simple.
You'll need wheat to make bread, to do this you'll need a hoe, and some water, as well as seed, you can punch the grasses you see and seeds should pop out eventually. (Not the dirt grass block, just the grass).
Once you have the seeds (3 or more) Till the grass next to the water to reveal the dirt and plant the seeds, you can tell they have grown when the crop is a murky yellow colour. Once you have 3 pieces of wheat go to a crafting table and craft the Bread!