You are using Lightning if you have a calendar in Thunderbird. Just the latest version comes with it bundled. Thunderbird synchronizes using caldav. In the caldav equation Lightning is a client. So you need a caldav server to synchronize with. The one of the popular choices is Google. But your can use many other caldav providers on the web. Some Free some paid. I personally use GMX, simply because it is free and in Europe. I am in Australia, but I just like to make following me as difficult as I can for the Government snoops. They can probably get access to GMX stored data, but it just makes their job harder. My tax dollars at work. The wikipedia page lists a number of client programs and server products and suppliers. Most server implementation are designed for "UNIX/Linux. But perhaps you could spin up your own server on windows, I just don't know of a windows server product. Although a Google search did pop up this product http://radicale.org/