Get 1 Brewing Stand
Get 1 Blaze Powder
Get 1 Water Bottle
Get 1 Nether Wart
Get 1 Magma Cream
Put Blaze Powder in the Brewing Stand fuel slot
Put Water Bottle in a bottle slot
Brew the Water Bottle with Nether Wart to make an Awkward Potion
Put Magma Cream in the ingredient slot
Brew to make a Potion of Fire Resistance
Optional: add Redstone Dust to extend the duration
Optional: add Gunpowder to make a Splash Potion of Fire Resistance
Optional: add Dragon’s Breath to make a Lingering Potion of Fire Resistance