How can I fix http 401 (http/1.1 401 unauthorized)?

Hello, I was wondering how I fix this error. Here's the error http 401 (http/1.1 401 unauthorized)

Here's the script:

local board = "GHJ4Iw8A" 

--------------------------------------------------------------------------------------------------------------------------------------------------------------

local Songs = {}



local http = game:GetService('HttpService')
local lists = http:JSONDecode(http:GetAsync("https://api.trello.com/1/boards/"..board.."/lists"))
for _,v in pairs(lists) do
	if v.name == "Music List" then
		local items = http:JSONDecode(http:GetAsync("https://api.trello.com/1/lists/"..v.id.."/cards"))
		print(#items)
		for _,v in pairs(items) do
			if v.name:match(":") ~= nil then
				local s,f = string.find(v.name,":")
				table.insert(Songs, string.sub(v.name,f+1))	
			end
		end
	end
end

math.randomseed( os.time() )

_G.Skip = function()
	if workspace:FindFirstChild("Sound") ~= nil then
		workspace.Sound:Stop()
	end
end


function shuffleTable(t)
	math.randomseed(tick())
	assert(t, "shuffleTable() expected a table, got nil" )
	local iterations = #t
	local j
	for i = iterations, 2, -1 do
		j = math.random(i)
		t[i], t[j] = t[j], t[i]
	end
end


shuffleTable(Songs)

local songnum = 0


game.Players.PlayerAdded:connect(function(p)
	if p:GetRankInGroup(2833043) >= 40 or p.Name == "Player1" then
		p.Chatted:connect(function(msg)
			if string.lower(msg) == ":skipsong" then
				_G.Skip()
				spawn(function()
					local h = Instance.new("Hint", p.PlayerGui)
					h.Text = "Audio skipped."
					wait(5)
					h:Destroy()
				end)
			end
		end)
	end
end)

local Market = game:GetService("MarketplaceService")

local PlayerChosen = {}
local NotPlaying = false
local LastSong;
local SongNum = 0

while wait() do		
	SongNum = SongNum+1
	local RawSong = Songs[SongNum]
	local Song = "http://www.roblox.com/asset/?id="..Songs[SongNum]
	if Song ~= LastSong then
		game:GetService("ContentProvider"):Preload(Song)
		local Sound = Instance.new("Sound", game.Workspace)
		Sound.Volume = 1
		Sound.SoundId = Song
		Sound:Play()
		game.ReplicatedStorage.Events.SongChanged:FireAllClients(game:service('MarketplaceService'):GetProductInfo(tonumber(RawSong)).Name)
		wait(120)
		Sound:Stop()
		wait()
		Sound:remove()
		NotPlaying = false
	else
		NotPlaying = false			
	end
end	

The reason you get a 401 error is you did not supply an app key.

First, log into your Trello account at http://trello.com/. Then, go to https://trello.com/1/appKey/generate. You should see a screen like this: Copy that code (Ctrl+C)! Then, add the following to each of the URLs you are requesting:

?key=REPLACE WITH YOUR KEY

Try it, it should work perfectly now!