A shop

#1 You will have to program the intricacies of a shop depending on how simple or complex you wish to make it. I would recommend learning TorqueScript and how to manipulate variables. From there, learn the GUI and how to increment and decrement inventory based upon moving things from the "shop" to the "player" and then you'll start to have an idea of how to put together a shop.

#2 Ok but where can i lern torque script the starter guide dosen't help with that

#3 Ok but where can i lern torque script the starter guide dosen't help with that

#4 There's some great books out there. Kenneth Finney's "3d Game Programming All in One" or 3dgpaio as people shorten it to is a great resource to learn to program and design things such as this.

The way you could make a shop would require no AI at all unless the shopkeeper were to be an actual citizen too (which in most MMO's and RPG's they aren't, they just stand there with dialogue trees) would be to give the player a variable for how much money they have, create a GUI with all the items for sale listing prices, maybe some stuff the shopkeeper says when you buy/sell. Then when the player clicks the buy button next to the item, it subtracts that much from their money, if they don't have enough it puts their money back and refuses the item. If they have enough money it subtracts it and adds that item to their inventory. You'd also need a GUI for the player inventory and some signifigant changes so it isn't the current I GOT GUNZ AND AMMO fps style inventory.

I read you're making an MMO, you may want to start small before designing something big like that, look at games such as WoW and how big the world is, how many NPC's they have and all the items. Each one of those takes forever to design, and without alot of experience and a team, most MMO's don't ever finish. I'm not trying to discourage you, just saying to try to get a bit more experience before going triple A. :D