How to make a gui that appears to everyone?

Help and Feedback Scripting Support
1

Is it like this?

script.Parent.Visible = true

But with Server Scripts?

2

You can use a RemoteEvent for that.
For example:

-- (Let's say the RemoteEvent is called "RemoteEvent")
-- In a Server Script:
game.ReplicatedStorage.RemoteEvent:FireAllClients()

-- And in your localscript:
game.ReplicatedStorage.RemoteEvent.OnServerEvent:Connect(function()
print("Your code here"))