How do I make a game like thee graveyard?

I want to make a game like the graveyard where you can buy something then you own it for every server but I cant figure out the purchase mechanism I am still new to scripting and havent learned quite how yet

as of right not I have a click detector and a script that say if parent.click = true then print(playername) but I dont know how to do the purchase or make it so the player name actually goes in that spot so pls help.