How does one create a randomizer game? Me and my friend need help.

You could put all the weapons in a dedicated folder in ServerStorage or somewhere and use GetChildren() to get a table with all the weapons. You can use the math.random function to choose a random weapon from the table every time and clone it to the player

local ServerStorage = game:GetService("ServerStorage")
local Players = game:GetService("Players")

-- table with all the weapons
local allWeapons = ServerStorage.Weapons:GetChildren()

Players.PlayerAdded:Connect(function(player)
    player.CharacterAdded:Connect(function(character)
        -- whenever somebody spawns or respawns, this will run

        -- select a random weapon, from 1 (the beginning of the table) to the last value in the table, clone it, and put it in the player's backpack
        local randomWeapon = allWeapons[math.random(1, #allWeapons)]:Clone()
        randomWeapon.Parent = player.Backpack
    end)
end)