how do I make/create a guy that sells items
First, create a shop in World > Shops. Add the items you want in the shop, then click on each item and add a player attribute to set their price. Unfortunately you cannot make items cost a variable, so you have to use attributes instead.
On the unit type of the unit that you want to sell items, add a script like this:
This will make a shop open for anyone who approaches the unit.
my version doesn’t have that trigger
You should use the newer version then.