How do i make a chair purchase system

okay i’m making a game where if you get wins you can buy chairs so when you sit on a basic one it changes it to the one you purchased and when you get off it reverts back to normal. its a cool concept from this game: da amazing bunker simulator [egg hunt 🥚] - Roblox
here is an example of the thing i need robloxapp-20210408-1033443_Trim.wmv (525.6 KB)

i don’t have any idea on what to do because i am not a master scripter