Create Shop:
To set the sold item, you should first put your item in the first slot in the chest
Place a sign on a chest
Write in first Line [Shop] to create a shop.
in the 2nd line you can set the selling price (e.g. 100 = 100$)
now you can click on Done, and your store sign should have been created
Good luck on your stores!
Is there a designated marketplace where we could all build our stores together?