error A using namespace directive can only be applied to namespaces; 'System.Windows.Forms.Application' is a type not a namespace C:\Users\Surya\documents\visual studio 2010\Projects\menuForm\Program

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 menuForm
{
    public partial class Form3 : Form
    {
       private void calculatefee()
       {
           int coursefee;
           switch(cmbcourse.SelectedIndex)
           {
               case 0:coursefee=7500;
                   break;
               case 1:coursefee=6000;
                   break;
               case 2:coursefee=4000;
                   break;
               case 3:coursefee=3000;
                   break;
               default:MessageBox.Show("please select a course!","Error");
               cmbcourse.Focus();
                   return;
           }
           if(rbafternoon.Checked)
               coursefee=coursefee*80/100;

           else if(rbmorning.Checked)
               coursefee=coursefee*90/100;
           if(chkcoursematerial.Checked)
               coursefee+=500;
           lblfee.Text=coursefee.ToString();
       }

        private void rbmorning_CheckedChanged(object sender, EventArgs e)
        {
            calculatefee();

        }

        private void rbafternoon_CheckedChanged(object sender, EventArgs e)
        {
            calculatefee();
        }

        private void rbevening_CheckedChanged(object sender, EventArgs e)
        {
            calculatefee();
        }

        private void chkcoursematerial_CheckedChanged(object sender, EventArgs e)
        {
            calculatefee();
        }

        private void cmbcourse_SelectedIndexChanged(object sender, EventArgs e)
        {
            calculatefee();
        }
    }
}