Help with Firing a remote event and getting Argument 1 missing?

When you use FireClient, it has a few parameters. First, you have to specify in the first argument what player you want to fire the remote event to. Type in something like this:

local debounce = false
game.Workspace.EverythingTP.ClickDoorArch1.ClickDetector.MouseClick:Connect(function(hit) 		 
    print("touched") 
    if not debounce then 
        print("about to start event") 
	game.ReplicatedStorage.Events.Gui:FireClient(player) --insert player to fire the event to 
	print("event started") 
    end 
end) 

If you want all players to receive it, do this:

local debounce = false
game.Workspace.EverythingTP.ClickDoorArch1.ClickDetector.MouseClick:Connect(function(hit) 		 
    print("touched") 
    if not debounce then 
        print("about to start event") 
	game.ReplicatedStorage.Events.Gui:FireAllClients
	print("event started") 
    end 
end) 

Hope this works. If it does not, then let me know.