From Web Forms to Windows Forms

public class Degree
{
    private MCX_COLLEGE_Data_ClassesDataContext _ds = new MCX_COLLEGE_Data_ClassesDataContext();
    private string Error = string.Empty;
    private int i = 0;

    public Degree()
    {
    }

    public string Error_Exception
    {
        get
        {
            return Error;
        }
        set
        {
            Error = value;
        }
    }
    public IList<degree> GetDegree()
    {
        return _ds.DEGREEs.ToList();
    }
    public IList<degree> GetDegree(int DegreeID)
    {
        IList<degree> _DegreeList = _ds.DEGREEs.ToList();

        var _List = from P in _ds.DEGREEs
                    where P.DegreeID == DegreeID
                    select P;

        if (_List.Count() > 0)
        {
            _DegreeList = _List.ToList();
        }
        return _DegreeList;
    }

    public int Save(int ParID, DEGREE _degreetbl)
    {

        using (var MyTran = new TransactionScope())

            try
            {
                _ds.Connection.Open();
                _ds.SP_DEGREE
                    (
                      ParID,
                     _degreetbl.DegreeID,
                     _degreetbl.Description,
                     _degreetbl.Duration_Years
                     );

                _ds.SubmitChanges();
                MyTran.Complete();
            }
            catch (Exception ex)
            {
                _ds.Connection.Close();
            }
         return ParID;

private Degree _d = new Degree();
     private DEGREE _degtbl = new DEGREE();
     private int _Results = 0;

     private Enum_Class _enum = new Enum_Class();

     private string _ApplicationMessage = string.Empty;

     protected void Page_Load(object sender, EventArgs e)
     {
         if (!Page.IsPostBack)
         {
             ViewState["PageMode"] = "Save";
             this.Populate();
         }

     }


     public void Populate()
     {
         grdDegree.DataSource = _d.GetDegree();
         grdDegree.DataBind();
     }
     public int Save()
     {
         _degtbl.DegreeID = 0;
         _degtbl.Description = txtDescription.Text;
         _degtbl.Duration_Years = Convert.ToInt32(txtDuration.Text);
         return _d.Save((int)Enum_Class.SQL_Parameters.Save, _degtbl);
     }
     public int Update()
     {
         _degtbl.DegreeID = int.Parse(ViewState["DegreeID"].ToString());
         _degtbl.Description = txtDescription.Text;
         _degtbl.Duration_Years = int.Parse(txtDuration.Text);
         return _d.Save((int)Enum_Class.SQL_Parameters.Update, _degtbl);
     }
     public int Delete()
     {
         _degtbl.DegreeID = int.Parse(ViewState["DegreeID"].ToString());
         _degtbl.Description = txtDescription.Text;
         _degtbl.Duration_Years = int.Parse(txtDuration.Text);

         return _d.Save((int)Enum_Class.SQL_Parameters.Delete, _degtbl);
     }


     protected void btnSubmit(object sender, EventArgs e)
     {
         switch (ViewState["PageMode"].ToString())
         {
             case "Save":

                 switch(this.Save())
                 {
                     case 1:
                         _ApplicationMessage = _d.Error_Exception;
                         lblError.Text = _ApplicationMessage;
                         lblMessage.Visible = true;
                         break;

                     case 0:
                         _ApplicationMessage = "Degree sucessfully submited";
                         lblMessage.Text = _ApplicationMessage;
                         lblMessage.Visible = true;

                         this.NoDuplicate();
                         break;


                 }
                 break;

             case "Upade":

                 switch(this.Update())
                 {
                     case 1:
                         _ApplicationMessage = _d.Error_Exception;
                         lblError.Text = _ApplicationMessage;
                         lblError.Visible = true;
                         break;

                     case 0:
                         _ApplicationMessage = "Degree sucessfully updated submited";
                         lblMessage.Text = _ApplicationMessage;
                         lblMessage.Visible = true;

                         this.NoDuplicate();
                         break;
                 }
                 break;

             case "Delete":

                 switch (this.Delete())
                 {
                     case 1:
                         _ApplicationMessage = _d.Error_Exception;
                         lblError.Text = _ApplicationMessage;
                         lblError.Visible = true;
                         break;

                     case 0:
                         _ApplicationMessage = "Degree Deleted";
                         lblMessage.Text = _ApplicationMessage;
                         lblMessage.Visible = true;
                         break;
                 }
                 break;

         }
         this.Populate();
     }

     protected void btnDelete(object sender, EventArgs e)
     {
         txtDescription.Text = "";
         txtDuration.Text = "";
     }
     public void NoDuplicate()
     {
         txtDescription.Text = "";
         txtDuration.Text = "";
         this.Populate();
         ViewState["PageMode"] = "Save";
     }

     protected void grdDegree_SelectedIndexChanged(object sender, EventArgs e)
     {
         GridViewRow _Rows = grdDegree.SelectedRow;
         string str = _Rows.Cells[0].Text;
         ViewState["DegreeID"] = str;

         IList<degree> _Edit = _d.GetDegree(int.Parse(str));

         if(_Edit != null)
         {
             foreach (DEGREE _degreeList in _Edit)
             {
                 ViewState["DegreeID"] = _degreeList.DegreeID.ToString();
                 txtDescription.Text = _degreeList.Description;
                 txtDuration.Text = _degreeList.Duration_Years.ToString();

             }
         }
         ViewState["PageMode"] = "Update";
     }</degree></degree></degree></degree>