i got error "The name 'SqlHelper' does not exist in the current context"

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Data.SqlClient;
using System.Data.SqlTypes;
using System.Data.Sql;



/// <summary>
/// Summary description for infoaddup
/// </summary>
public class infoaddup
{
    infoaddup objinfo = new infoaddup();
    int Id;
    public int id
    {
        get { return Id; }
        set { Id = value; }
    }
    string Name;
    public string name
    {
        get { return Name; }
        set { Name = value; }
    }
    string Last_Name;
    public string last_Name
    {
        get { return Last_Name; }
        set { Last_Name = value; }
    }
    string Ph;
    public string ph
    {
        get { return Ph; }
        set { Ph = value; }
    }

    public infoaddup()
    {
        try
        {
            SqlParameter[] p = new SqlParameter[4];
            p[0] = new SqlParameter("@Id", SqlDbType.Int);
            p[0].Value = Id;
            p[1] = new SqlParameter("@Name", SqlDbType.NVarChar);
            p[1].Value = Name;
            p[2] = new SqlParameter("@Last_Name", SqlDbType.NVarChar);
            p[2].Value = Last_Name;
            p[3] = new SqlParameter("@Ph", SqlDbType.NVarChar);
            p[3].Value = Ph;

          //  int i = SqlHelper.ExecuteNonQuery(clsConnection.ConnectionString, CommandType.StoredProcedure, "ConsineeMaster_AddUpdate", p);
            int i = SqlHelper.ExecuteNonQuery(infoaddup.ConnectionString, CommandType.StoredProcedure, "infoaddup", p);
        }
        catch (Exception ex)
        {
            clsErrHandler.WriteError(ex);
        }

    }
   
}