If you're not using the container your juice comes in, pour one gallon of grape juice into your container.
Pull up the sweetness calculator, and decide how sweet you'd like your juice.
Using the values from the sweetness calculator, pour out some juice (you can save it to backsweeten with later) and add your sugar. Then, shake it all up!
Open your brewsy bag and pour the contents in. Seal your juice again and shake well.
Apply the airlock, then leave your container somewhere dark and warm (75-80°F is best) for 3 days.
After 3 days, move it to the fridge for 48 hours. You can remove the airlock and set the original cap on top of your drink. Be sure not to tighten the cap!
After 48+ hours in the fridge, your yeast will have fallen to the bottom of your container.
Now, carefully "rack" your wine by pouring it off of the sediment into a different container. You can discard the sediment at the bottom — you won't want it in your final product. Then, pour a glass and give it a try!
Store the rest of your wine in the fridge, with the bottle cap still on loosely.
If you see sediment start to build up again after several days, you can rack it again. As it ages, the taste of your wine will keep on getting better.