i am trying to make my iron man helmet open and close can somebody help?

You cant use mouseButton1Click on the server.

Do the mouse click on the client, then fire a remote event to the server, then make a function for setting the Helmet transparency to 0 (or 1)

Example

client

local event = path_to_your_event

button.MouseButton1Down:Connect(function()
	--could add a simple debounce here
	event:FireServer(1) --we are going to fire 1 as the argument
end)	

server

local event = path_to_your_event
local helmet = path_to_helmet

 --we are going to make sure given transparency is a number so we add the :number 
local function setHelmetTransparency(Player, givenTransparency: number)
	--player is the player that fired the event
	--givenTransparency is the number we passed as an argument on the client

	helmet.Transparency = givenTransparency
end

event.OnServerEvent:Connect(setHelmetTransparency) --this is how we receive remote events on the server