You need to beat 10 levels of AI in Play VS Computer. I would recommend doing levels 1 - 10 to make this quicker and easier.
To make thing even easier and quicker I recommend using a chess engine to help while you play. I used
https://nextchessmove.com/If you play on Windows 7/8/10, you can snap the chess engine and Simply Chess to the sides of your screen so you can play and get chess help at the same time.