[Solved] Create a JSON Rest Service in ASP.Net

I was told to build a rest web service using asp.net so does the code below represent the same

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Services;
using System.Data;
using System.Data.SqlClient;

namespace Jquery
{
    /// <summary>
    /// Summary description for WebService
    /// </summary>
    [WebService(Namespace = "http://tempuri.org/")]
    [WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
    [System.ComponentModel.ToolboxItem(false)]
    // To allow this Web Service to be called from script, using ASP.NET AJAX, uncomment the following line. 
    [System.Web.Script.Services.ScriptService]
    public class WebService : System.Web.Services.WebService
    {
        [WebMethod]

        public string GetAgentDetails(string JsonAgentUsernameAndPassword)
        {
            string username = "", password = "";

            Agent agentDetails = new System.Web.Script.Serialization.JavaScriptSerializer().Deserialize<Agent>(JsonAgentUsernameAndPassword);

            //will get only one entry
            foreach (var items in agentDetails.data)
            {
                username = items.username;
                password = items.password;
            }


            DataTable dt = new DataTable();
            using (SqlConnection con = new SqlConnection("Data Source=SureshDasari;Initial Catalog=master;Integrated Security=true"))
            {
                string cmdtxt = "select * from Tbl_Login where username=" + username + "and password =" + password;
                using (SqlCommand cmd = new SqlCommand(cmdtxt, con))
                {
                    con.Open();
                    SqlDataAdapter da = new SqlDataAdapter(cmd);
                    da.Fill(dt);
                    System.Web.Script.Serialization.JavaScriptSerializer serializer = new System.Web.Script.Serialization.JavaScriptSerializer();
                    List<Dictionary<string, object>> rows = new List<Dictionary<string, object>>();
                    Dictionary<string, object> row;
                    foreach (DataRow dr in dt.Rows)
                    {
                        row = new Dictionary<string, object>();
                        foreach (DataColumn col in dt.Columns)
                        {
                            row.Add(col.ColumnName, dr[col]);
                        }
                        rows.Add(row);
                    }
                    return serializer.Serialize(rows);
                }
            }
        }
    }
    public class Agent
    {

        public List<AgentDetails> data { get; set; }
    }

    public class AgentDetails
    {

        public string username { get; set; }
        public string password { get; set; }
    }
}