Connecting developer products to the game?

So I recently created a developer product for my WIP game, and I have no idea how to link it to the game. I want to make it so that when you click on a specific block, you would be given the option to buy it right away, but I'm not sure how you do it. You start with an onClicked function, I'm assuming?

http://wiki.roblox.com/index.php?title=Developer_product