Gather 1 Nether Wart
Gather 1 Glistering Melon Slice
Gather 1 Water Bottle
Gather 1 Blaze Powder
Open a Brewing Stand
Put Blaze Powder in the fuel slot
Put the Water Bottle in a bottom slot
Add Nether Wart to make an Awkward Potion
Add Glistering Melon Slice to make a Potion of Healing
Use Redstone to make it last longer if needed
Use Glowstone Dust to make it stronger if needed