how can i scroll trough my backpack?

So i want that if you scroll forward / backward you change your gun to the next gun so if u have 2 guns if u have the main selected and if u scroll then it changes to ur secondary and then if u scroll again it goes back to ur main! code:

local Player = game:GetService("Players").LocalPlayer;
local Backpack = Player:WaitForChild("Backpack");
local Mouse = Player:GetMouse();
local text = "Changing Weapon";
local Character = Player.Character;
local Hum = Character:WaitForChild("Humanoid")

local ChangeWeapon = function()
    print(text);
    local Guns = Backpack:GetChildren();
    for i=1, #Guns do
        Hum:EquipTool(Guns[1]);
    end
end

local ChangeWeapon1 = function()
    print(text);
    local Guns = Backpack:GetChildren();
    for i=-1, #Guns do
        Hum:EquipTool(Guns[1]);
    end
end

Mouse.WheelForward:connect(function()
    ChangeWeapon()
end);


Mouse.WheelBackward:connect(function()
    ChangeWeapon()
end);

this does not work! D: (asking again since it got moderated =,=)