Twine Store System Help

Hello! I was curious if someone could explain to me on how I could go about programming a shop in my game. How to add and remove cash from my inventory, etc. Sorry if this question has been previously asked, I could not find an answer. Thank you and have an amazing day :smiley:

Please specify version and format if asking for help, or apply optional tags above:
Twine Version: 2
Story Format: Harlowe