The "key is not working

I followed a tutorial on C # and when he wrote this:

using System;

namespace test
{
	class MainClass
	{
		public static void Main (string[] args) //
		{
			Console.WriteLine ("hello world")
		}
	}
}

but the (“hello world”) I can not type because I can not use the "key.
the key itself does work on the Internet or word.

I’m just a beginner.
pls help

The code that you wrote is for C# that is compiled to an executable. It’s meaningless for Unity. If you want to learn Unity C#, use a C# tutorial specific to Unity.