How do I make a screen fade away on click?

Hi, So I been trying to make a fade screen script. What does it do may you be asking? Well when a player clicks a part there screen fades to black and then there screen fades back and they get teleported to another position not a another game. The thing is that I don't know how to get to a Player's Gui.

function onClicked(plr)
    plr.Character.HumanoidRootPart.CFrame = script.Parent.To.CFrame 
end
script.Parent.Click.ClickDetector.MouseClick:Connect(onClicked)