main category and sub category bind in json body using nested list

public class _maincategory {
public class maincat { private string mCatid; [DataMember(Order = 0)] public string ImCatid { get { return mCatid; } set { mCatid = value; } }

        private string mCatName;
        [DataMember(Order = 1)]
        public string ImCatName
        {
            get { return mCatName; }
            set { mCatName = value; }
        }


        private List<Items> orderItems;
        [DataMember(Order = 2)]
        public List<Items> IorderItems
        {
            get { return orderItems; }
            set { orderItems = value; }
        }
    }

    public class Items
    {
        private string Catid;
        [DataMember(Order = 0)]
        public string ICatid
        {
            get { return Catid; }
            set { Catid = value; }
        }


        private string CatName;
        [DataMember(Order = 1)]
        public string ICatName
        {
            get { return CatName; }
            set { CatName = value; }
        }

        private string CatImgUrl;
        [DataMember(Order = 2)]
        public string ICatImgUrl
        {
            get { return CatImgUrl; }
            set { CatImgUrl = value; }
        }

    }
}   

public List<_maincategory.maincat> menuCategory() { var dt = objDut.GetDataTable("select mCatid,mCatName from pm_Product_menuCategory where mcatactive=1 order by mCatid"); if (dt.Rows.Count > 0) { var strQurey = from dr in dt.AsEnumerable() select new _maincategory.maincat {

                ImCatid = dr["mCatid"].ToString(),
                ImCatName = dr["mCatName"].ToString(),
                IorderItems = new List<_maincategory.Items>
                {
                       new _maincategory.Items
                       {

                           ICatid = "nn",
                           ICatName = "wsds",
                           ICatImgUrl = "asxsx",                              
                       }
                }             

            };
            return strQurey.ToList();

        }
        return null;           
    }