FakeArms to Head Weld?

I heard that if you weld the arms to the head and add a head moving with cursor script, then it will look up and down, so I want to know, how would I properly type the script?

for FPS I prefer to use R6 real arms this is my local script:

plr = game.Players.LocalPlayer;
repeat wait() until plr.Character
char = plr.Character
m = plr:GetMouse()
game["Run Service"].RenderStepped:connect(function()
local c = game.Workspace.CurrentCamera

char.HumanoidRootPart["RootJoint"].C0 = CFrame.new(0,0,0) * CFrame.Angles(-math.asin((m.Origin.p - m.Hit.p).unit.y) + 1.55,3.15,0)

	char.Humanoid.CameraOffset = (char.HumanoidRootPart.CFrame+Vector3.new(0,0,0)):pointToObjectSpace(char.Head.CFrame.p + Vector3.new(0,-1.46,0))

end)

guys, yas all know am useless! look what I tried!

local function weldBetween(a, b, c)
    local weld = Instance.new("ManualWeld")
    weld.falsearm1 = a
    weld.Head = b
    weld.falsearm2 = c
    weld.C0 = CFrame.new()
    weld.C1 = b.CFrame:inverse() * a.CFrame * c.CFrame
    weld.C2 = CFrame.new()
    weld.Parent = b
    return weld;
end

plz help me guys!