This will be my 1st batch of wine. I am using blackberry concentrate. I do not like sweet wine. Can I decrease the heavy sugar content to make a less sweet wine? Thanks.
@Sharona,
Welcome to the hobby!
You'll add yeast, which will essentially eat all the sugar until there's none left, and creating alcohol in the process. That will mean a reading on your hydrometer of around 0.990, which is referred to as "dry" for it's lack of sugar. At that point, add potassium metabisulfite to the batch (1/4 teaspoon for 6 gallons); this is the stabilizing phase.
As long as you ferment all the way to dry, your wine will not be sweet. To get sweet wine, one has to stabilize with potassium metabisulfite and also add potassium sorbate, then add sugar of some kind to back-sweeten.
If you don't add those two chemicals, the yeast will just keep fermenting whatever sugar you add, making more alcohol, up to the limit the yeast can tolerate, which is most often around 18% alcohol.
Be sure you have a hydrometer before you start the batch, as that is a critical tool. Most folks take a starting gravity reading prior to adding the yeast.
Best of luck, feel free to ask questions along the way.