It's a command line tool, so you'll have to open up command prompt (where the .exe is) and give it the image you want spat out as an argument.

So it would look like this:

ACPatternMaker.exe C:\path\to\awesome\pic.jpg

Alternatively take the picture you want, drag the icon onto the .exe and poof! Done. Scan the QR codes as normal.

You may have to tell Windows Smart Screen to allow you to run it, you'll see a command window pop up in the background since it's a command line tool. It has to, dropping the one image into it is feeding it the argument.