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)