script is located in StarterCharacterScripts and it is LOCALSCRIPT
--------------------------VARIBLES-------------------------------------------
local Mouse = game.Players.LocalPlayer:GetMouse()
local player_model = script.Parent
local player_arm = player_model:FindFirstChild("LeftUpperArm")
local arm_motor = player_arm:FindFirstChild("LeftShoulder")
--------------------------VARIBLES-------------------------------------------
Mouse.Move:Connect(function()
arm_motor.Transform = CFrame.new(Vector3.new(0,0,0), Mouse.Hit.p)
end)