After we launch the application we start on the Main Menu. You'll see the four current features: Brew Tools, Brew Sessions, BCJP Categories and Beer Reviews.
As you might imagine, the ABV Calculator is located under Brew Tools.
Now, how do we get gravity? There are two preferred methods for homebrewers. It is typically done via a hydrometer or a refractometer. For those starting out, more than likely a hydrometer was included in your kit.
For my most recent Black IPA as an example, I had an original gravity of 1.078 and after six weeks it came back 1.022.
You'll notice that for the input Brewmaster assumes the starting 1. So you just need to fill in the rest. Type in '078' for original and '022' for final.
Now click Calculate, and off we go. This one clocks in at 7.9% ABV. It will be a fun beer to sip. Cheers!