Why is visual studio code printing C# to terminal correctly, but not output?

Question

I'm new to C#. I installed Visual Studio code along with the NET framework, and when I run my project in the terminal via 'dotnet run', everything works perfectly.

Yet, when I switch over to the output window I see this message --

Can anyone lead me in the right direction? I've been going at it for 10 hours now - research, reinstalls, and restarts galore - yet nothing seems to help. Again I stress: in the visual studio terminal, the code works fine.

What gives?

Edit: I manually added scriptcs to path, and now the error has change - "You cannot declare namespace in script code"

using System;
namespace HelloWorld
{
    class Hello 
    {
        static void Main() 
        {
            Console.WriteLine("Hello World!");

            // Keep the console window open in debug mode.
            Console.WriteLine("Press any key to exit.");
            Console.ReadKey();
        }
    }
}

This is what happens without namespace; still no output.

Answer 1

Turns out, I had to get rid of everything aside from:

Console.WriteLine("Hello World!");      
Console.WriteLine("Press any key to exit.");
Console.ReadKey();

I don't know why, but now 'run dotnet' in terminal doesn't work, yet the output does. Regardless, thanks to everyone who helpeD!!!