Im trying to use code to make it so it creates a hair mesh for the player?

If your hair is from the catalog, you can easily use InsertService

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

function playerAdded(player)
    player.CharacterAdded:connect(function(character)
        removeAccessories(character)
        changeHair(character, 16630147) -- paste hair id, has to be created by you or ROBLOX or it wont work
    end)
end

function removeAccessories(character)
    for _, v in pairs(character:GetChildren()) do 
        if v:IsA("Accessory") then 
            v:Destroy()
        end
    end
end

function changeHair(character, hairid)
    local ContainerModel = InsertService:LoadAsset(hairid) -- when you insert something, it automatically creates a model and sets the asset's parent to the model

    for _, v in pairs(ContainerModel:GetChildren()) do 
        if v:IsA("Accessory") then 
            v.Parent = character
            ContainerModel:Destroy()
        end
    end
end

Players.PlayerAdded:connect(playerAdded)