how do you add a in game catalog ?

i was in a game and i thought to my self how does it work to add a in game catalog and users could spend in game money to buy the stuff ?

First, it sounds like you aren't very experienced with RBX.Lua, if at all. In case you are, here are the things you would need to know --

• MarketPlaceService
• GUIs
• Local Scripts

However, based upon what your level of scripting seems to be, this is the best place to start --

• This handy page

For things like in-game catalogs, it is much better to have ample coding knowledge before even attempting it. Many things can go wrong which will negatively effect your game and yourself, as well as give you a major headache attempting to implement it.

Good luck!