for_field.cs

        static void Main(string[] args)
        {
            int width = 80;
            int height = 20;
            
            // iterate each y
            for (int y = 0; y < height; y++)
            {
                // iterate each x
                for (int x = 0; x < width; x++)
                {
                    // draw a sharp if we are at the edges of the terminal
                    if (x == 0 || x == width - 1 || y == 0 || y == height - 1)
                    {
                        Console.BackgroundColor = ConsoleColor.DarkGreen;
                        Console.ForegroundColor = ConsoleColor.Red;
                        Console.Write("#");
                    }
                    // othwerwise draw a space to advance the cursor
                    else
                    {
                        Console.BackgroundColor = ConsoleColor.Black;
                        Console.ForegroundColor = ConsoleColor.Black;
                        Console.Write(" ");
                    }
                }
                // end of a line, go below
                Console.WriteLine();
            }

            Console.ReadLine();
        }