How do I make the LeftPunch function do damage?

I am trying to make the LeftPunch function do damage. But I can't figure it out. I would love it if someone helped me!

Player = game.Players.LocalPlayer
Character = Player.Character
Mouse = Player:GetMouse()

LeftShoulder = Character.Torso["Left Shoulder"]
RightShoulder = Character.Torso["Right Shoulder"]
LeftHip = Character.Torso["Left Hip"]
RightHip = Character.Torso["Right Hip"]

function LeftPunch(key)
	Key = key:lower()
	if Key == "q" then
		for i = 1, 1 do
			for i = 1, 10 do
				LeftShoulder.C0 = LeftShoulder.C0 *CFrame.Angles(0, 0, -0.25)
				wait()
			end
			for i = 1, 10 do
				LeftShoulder.C0 = LeftShoulder.C0 *CFrame.Angles(0, 0, 0.25)
				wait()
			end
		end
	end	
end

function RightPunch()
	
end

function LeftKick()
	
end

function RightKick()
	
end

Mouse.KeyDown:connect(LeftPunch)