Chest shops are quite simple, and I'll tell you the steps in order. First you put a sign on a chest and type your name on the top line. Then, go on to the second line and put how much of the item you are going to sell/buy whenever somebody clicks on it. Next, you have to go to the third line and put B or S and a price. (B-Buy S-Sell) Finally you move onto the last line and put the item ID or the item's name. To obtain the ID, hold the item in your hand and type /iteminfo. If you have any questions, just ask. Hope this helped!
Or view this https://aemservers.net/threads/guide-how-to-make-chestshops.1227/ It has a picture on what you type each lane and how to get the item ID.
