HELP me please with Textprinter !

I cannot call textprinter. I have made all as in the instruction but when I write
ITextPrinter text = new TextPrinter()
or TextPrinter text =new TextPrinter()
i have an eror

error CS0246: The type or namespace name 'TextPrinter' could not be found (are you missing a using directive or an assembly reference?)

Here that I use

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Diagnostics;
using System.IO;
using OpenTK.Graphics.OpenGL;
using OpenTK.Graphics.OpenGL.Enums;
using OpenTK.Input;
using OpenTK.Graphics;
using OpenTK;