Here am inserting the Json data into MongoDB by passing the values from c# code, here am accessing the "test"database to insert the piece of data, Add MongoDB refference to the solution and access them in the class file.
Find the below console application code to insert the details into MongoDB

using System;
using System.Collections.Generic;
using MongoDB.Driver;
using MongoDB.Bson;

namespace InsDtls
    class Program
        static void Main(string[] args)
            var Client = new MongoClient();
            var DB = Client.GetDatabase("test");  
            var collection = DB.GetCollection<BsonDocument>("store");
            var documnt = new BsonDocument
                {"ProductName","Sony Earphones"},
                {"Made in","US"}
            Console.WriteLine("Press Enter to insert the data");