How to add the (WaitForChild) to this to make it work?

The first script is "PowerOutage" and the below one is "Gate"

local m = Instance.new("Hint", game.Workspace)
 m.Text = "Main Computer Offline!"
 m.Name = "Offline"
	game.Workspace.Gate.PowerOutage.PowerOutageSound:play()
	game.Lighting.TimeOfDay = 0
	game.Lighting.Brightness = 0
	game.Lighting.Ambient = Color3.new (0, 0, 0)
wait(3)
m:remove()

What do I add to this script below to make the script above work? The above script is in the properties of the bottom script and is not local, and is in the workspace. Also filtering is disabled. Everything in the above script works EXCEPT for the parts that adjust the lighting. The lighting part of the script only works in testing, but not actually in a server.

script.AnnouncementsSafe:Play()
wait(4)
script.ReactorSafe2:Play()
wait(6)
script.Alarmy:play()
wait(20)
script.music1:play()
wait(3)
script.Beginning:play()
wait(20)
script.emgevac:Play()
wait(18)
script.emgevac:Play()
wait(15)
script.explosionimminent:Play()
wait(7)
script.emgevac:Play()
wait(20)
wait(2)
script.actionmusic:Play()
wait(3)
script.firemergency:Play()
wait(10)
script.emergencypower:Play()
wait(7)
script.coreexplosionimminent:Play()
wait(9)
wait(11)
script.firemergency:Play()
wait(17)
script.fourminutes:Play()
wait(1)
wait(3)
script.nuclearalarm:Play()
script.actionmusic:Stop()
script.matrix1:Play()
wait(15)
local m = Instance.new("Hint", game.Workspace)
 m.Text = "Evacuate Starbase - IMMEDIATELY! "
 m.Name = "Evac"
wait(11)
wait(4.2)
m:remove()
-- SCRIPT ABOVE ENABLED BELOW --
game.Workspace.Gate.PowerOutage.Disabled = false
local m = Instance.new("Hint", game.Workspace)
 m.Text = "MAIN COMPUTER OFFLINE! - NO POWER"
 m.Name = "OUTAGE"
wait(15)
m:remove()
local m = Instance.new("Hint", game.Workspace)
 m.Text = "Evacuate Starbase - IMMEDIATELY ! "
 m.Name = "Evac"
wait(19)
wait(39)
m:Remove()
script.timerdestroyed:Play()
wait(9)
script.selfdestruct:Play()
wait(8)
script.alarmmain2:Play()
local msg = Instance.new("Message")
msg.Parent = game.Workspace
msg.Name = 'HelloBrick'
msg.Text = "Warning - Computer Self Destruct Initiated"
wait(5)
msg.Text = "Have a wonderful day :)"
wait(3)  
game.Workspace.HelloBrick:Remove()
script.matrix1:Stop()
script.matrix2:Play()
script.Countdown.Disabled = false

In order to do a WaitForChild you simply use:

local Lighting = game:WaitForChild("Lighting")
Lighting.TimeOfDay = 0
Lighting.Brightness = 0