Need explanation for mouseclicks

So I'm trying to make a program, that when you click somewhere, something happens. But I don't get how to do it. If I click at position 5,6 for example I want something to happen, can someone make a example code and explain it?

Use events to caputre where the click took place and use an if statement to check if it was in a location that it needs to do something.

local event, button, mouseX, mouseY = os.pullEvent("mouse_click")
if mouseX == 5 and mouseY == 6 then
--do stuff
end

Thank you good sir!