Save character unlock in json

Hello, I am making a mobile game where I can buy characters with gold and I wanted to know how to save that data in a json I mean save the data every time I buy a character and the gold that I have left, I want to save each character that I unlock in json so the player does not think about his progress. I am lost on this issue and I need help please someone.

 

1. Learn json
2. implement system.
3. Save json data.

Ok, in reality... have you looked at json tutorials? There are a ton of them out there. If you've tried something already, post your code and I'll be glad to help. If you haven't, then just go and try it. There are a ton of people who will help you if you post your attempt and are just getting stuck.