asp.net c# login class

I have the following code behind asp.net c#. It works fine, and now I want to put them into class and save in Bin folder.
Can you show me what I need to edit inside of the following codes, and save in class in bin folder?
and I will have login.aspx and use code behind to call the class back. How can I do that?
I will give out 500 pts for this question
Note: You can ignore the dbReader object, and simply return value (LoginChkCommand.Parameters["@retval"].Value)

protected void cmdlogin_Click(object sender, EventArgs e)
    {
        SqlConnection myConnection = new SqlConnection();
        try
        {
            //create db connection and open it
            string ConnectionString = ConfigurationSettings.AppSettings["DBconnection"];
            string CommandText = "up_IsValidLogon";
            myConnection.ConnectionString = ConnectionString;

            SqlCommand LoginChkCommand = new SqlCommand(CommandText, myConnection);
            LoginChkCommand.CommandType = CommandType.StoredProcedure;
            //need to add parameter
            //**********************
            SqlParameter var1 = new SqlParameter();
            var1.ParameterName = "@username";
            var1.SqlDbType = SqlDbType.VarChar;
            var1.Value = UserName.Text;
            LoginChkCommand.Parameters.Add(var1);

            SqlParameter var2 = new SqlParameter();
            var2.ParameterName = "@password";
            var2.SqlDbType = SqlDbType.VarChar;
            var2.Value = UserPass.Text;
            LoginChkCommand.Parameters.Add(var2);

            SqlParameter var3 = new SqlParameter();
            var3.ParameterName = "@retval";
            var3.SqlDbType = SqlDbType.Int;
            var3.Direction = ParameterDirection.Output;
            LoginChkCommand.Parameters.Add(var3);
            //**********************
              myConnection.Open();
              SqlDataReader myReader = LoginChkCommand.ExecuteReader();
              GridView1.DataSource = myReader;
              GridView1.DataBind();
              myReader.Close();
            //**********************
            //now get the output parameter:
            lblmsg.Text =  LoginChkCommand.Parameters["@retval"].Value
            //**********************
        }
        catch (Exception ex)
        {
            throw (ex);
        }
        finally
        {
            myConnection.Close();
        }

    }