How do you make an Order System for a cafe game on Roblox?

I'm trying to do the touch part or click detector to make the GUI open but can't figure out how. I kinda started a year ago on building Roblox games, I use tutorials on YT. So I might not understand everything but I'll try my best. By order system, I mean like the order computers like in irl restaurants. So the player clicks a button on a part/ touches a part it opens a GUI, has different options like food drinks, etc. Then you click the buttons to choose toppings then submit and the data shows on the queue in a kitchen.