using System.Windows.Forms; не подключается, выдает ошибку при web

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;

namespace браузер_аля_
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void back_Click(object sender, EventArgs e)
        {
            object p = System.Web.GoBack();
        }

        private void Front_Click(object sender, EventArgs e)
        {
            Web.GoForward();
        }

        private void Home_Click(object sender, EventArgs e)
        {
            Web.Navigate("https://www.ena.lp.edu.ua:8080//");
        }

        private void Refresh_Click(object sender, EventArgs e)
        {
            Web.Refresh();
        }

        private void toolStripTextBox1_Click(object sender, EventArgs e)
        {

        }

        private void Enter_Click(object sender, EventArgs e)
        {
            Web.Navigate(toolStrip1.Text);
        }

        private void Web_DocumentCompleted(object sender, 
WebBrowserDocumentCompletedEventArgs e)
        {
            toolStrip1.Text = System.Web.Url.ToString();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            Web.Navigate("www.yandex.com/");
        }
    }
}