Alright, this is a little tricky, so bare with me.
To start, extract the .zip file you downloaded by right-clicking on it and then left-clicking extract. Open the folder it creates and double-left-click on BarGenerator2.exe or whatever I called it.
Once it is open, left click on the big white button that says "Play". This will take you to a screen that has 2 big, white boxes. One of them will be blank, the other says "Generate". Click on the "Generate" button. There you go. Have fun!
If you are still stuck, here is a video that goes through the second half of the steps: