How would I add damage to this?

Hello,I inserted a localscript in starterpack and added this in the script. It works fine but I don't know how to add damage to it.Would I have to make a whole new script inside of this localscript? Any tips?

plr = script.Parent.Parent
local buttonPressed = false
mouse = plr:GetMouse()

	mouse.KeyDown:connect(function(key)
	key = key:lower()
	if key == "b" then
		 if not buttonPressed then
			 buttonPressed = true
			SmokeT = Instance.new("Smoke")
			SmokeH = Instance.new("Smoke")
			SmokeLL = Instance.new("Smoke")
			SmokeRL = Instance.new("Smoke")
			SmokeRA = Instance.new("Smoke")
			SmokeLA = Instance.new("Smoke")
			SmokeT.Parent = plr.Character.Head
			SmokeH.Parent = plr.Character.Torso
			SmokeLL.Parent= plr.Character["Right Arm"]
				SmokeRL.Parent= plr.Character["Left Arm"]
					SmokeRA.Parent= plr.Character["Right Leg"]
						SmokeLA.Parent= plr.Character["Left Leg"]
			wait(.5)
			game:GetService("Chat"):Chat(plr.Character.Head, "Explosion!")
				plr.Character.Head.Transparency = 1
			plr.Character.Torso.Transparency = 1
			plr.Character["Right Arm"].Transparency = 1
			plr.Character["Right Leg"].Transparency = 1
			plr.Character["Left Arm"].Transparency = 1
			plr.Character["Left Leg"].Transparency = 1
			SmokeE = Instance.new("Part")
			SmokeE.Parent = plr.Character.Torso
			SmokeE.Transparency = 0.7
			SmokeE.BrickColor = BrickColor.new("Quill grey")
			SmokeE.CFrame = CFrame.new(plr.Character.Torso.Position)
			SmokeE.Anchored = true
			SmokeE.CanCollide = false
			SmokeE.BottomSurface = "Smooth"
			SmokeE.TopSurface = "Smooth"
			SmokeE.Shape = "Ball"
			
wait(6)
		buttonPressed = false
		end
				end
		
		end)