How do I make an in-game purchase?

Can someone teach me how to do a in-game purchase for my gamepasses and shirts In some game I see them Please someone

Firstly, you need to be BC to sell anything apart from Developer Products. Click the link to learn more! Hope this helps :)

Roblox recently posted how to make a chat gui. look at it, understand it, then tweak it to where it creates an interactive gui. Then you insert the ID of your gamepass or item into the GUI so when its clicked, it should activate a window where it asks you if you want to buy the item.