How do I turn wire a light switch to a pointlight?

Start by Inserting the Part that you want your switch to be. Insert a ClickDetector object inside this Part and a script to it(not the Detector!)

Use this code to Enable/Disable your light

function onClicked()
    game.Workspace.PartWithPointLight.PointLight.Enabled = true --Or set it to false.
end

script.Parent.ClickDetector.MouseClick:connect(onClicked)

You can also have it, so every time you click the "switch" the light will open or if it's already then it will go away.

function onClicked()
    if game.Workspace.PartWithPointLight.PointLight.Enabled == false then
        game.Workspace.PartWithPointLight.PointLight.Enabled = true
    elseif game.Workspace.PartWithPointLight.PointLight.Enabled == true then
        game.Workspace.PartWithPointLight.PointLight.Enabled = false
    end
end

script.Parent.ClickDetector.MouseClick:connect(onClicked)