JSON is used to make a key value or collection pair of values while performing transfer of data. So i am inserting values into database using ajax call in which i first have created a user class for defining entities
.Example:

        public int id;
        public string Username;
        public string Password;
        public string Email;
        public int PrefernceID;
        public string Contact;
        public string Address;
        public string status;
        public string errormsg;
        public string Preference;
        public string acctype;

This is my User class and its associated entities.

After doing that i am making an AJAX call from the registration page into a method called Insert Details. For parsing values into JSON i have used JSON.stringify(user) and passed a user array object into it, see the example below:

       function InsertDetails() {
        var user = {};
        user.Username = $("[id*=txtUserName]").val();
        user.Password = $("[id*=txtPassword]").val();
        user.Email = $("[id*=txtEmail]").val();
        user.Contact = $("[id*=txtContact]").val();
        user.Address = $("[id*=txtAddress]").val();
        user.Preference = $("[id*=txtPreference]").val();
        $.ajax({
            type: "POST",
            url: "RegisterUser.aspx/InsertDetails",
            data: '{user: ' + JSON.stringify(user) + '}',
            contentType: "application/json; charset=utf-8",
            dataType: "json",
            success: function (response) {
                alert("User has been added successfully.");                    
                window.location.reload();
            }
        });
        return false;
    }

After doing this i will collect the values passed from user object and perform insertion operations into my Insert Details method, see the below example:

 [WebMethod]
        [ScriptMethod]
        public static void InsertDetails(User user)
        {
            try
            {
                UserOperation repobj = new UserOperation();
                user = repobj.GetPrefernceId(user);
                user = repobj.InsertData(user);

                }
catch(Exception ex)
               {
}
            }

            catch (Exception ex)
            {
                throw ex;
            }
        }

Here in above code i have used Script Method which is used to receive object coming from user .