what is the code should write inside businesslogiclayer?

namespace BusinessLogicLayer
{
    class BusinessClass
    {
        public string _Name;
        public int _Roll_number;
        public string _Email_Id;
        public string _Mobile_Number;

        DataAccessClass objdal = new DataAccessClass();

        public string Name
        {
            get
            {
                return _Name;
            }
            set
            {
                _Name = value;
            }
        }
        public int Roll_Number
        {
            get
            {
                return _Roll_number;
            }
            set
            {
                _Roll_number = value;
            }
        }
        public string Email_Id
        {
            get
            {
                return _Email_Id;
            }
            set
            {
                _Email_Id = value;
            }
        }
        public string Mobile_Number
        {
            get
            {
                return _Mobile_Number;
            }
            set
            {
                _Mobile_Number = value;
            }

        }

namespace DataAccessLayer
{
    public class DataAccessClass
    {
        //String cs = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;
        SqlConnection con;
        SqlCommand cmd;
        public DataAccessClass()
        {
            SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString);
            SqlCommand cmd = new SqlCommand("sp_InsertEmpdetails", con);
            cmd.CommandType = CommandType.StoredProcedure;
            cmd.Parameters.AddWithValue("@Name",objdal.Name);//here i could not access the objdal object why?please help me
            cmd.Parameters.AddWithValue("@Roll_Number", objdal.Roll_Number);//
            cmd.Parameters.AddWithValue("@Email_Id", objdal.Email_Id);
            cmd.Parameters.AddWithValue("@Mobile_Number", objdal.Mobile_Number);
            con.Open();
            cmd.ExecuteNonQuery();
            con.Close();
        }
    }

 }