If you need a quick solution to serializing your data into JSON, you might consider using Boost’s property_tree.
The Boost support for this is a “header-only” library, so it’s very portable and requires no run time installation. On top of that, the Boost distribution is excellent: clean, robust, and well-vetted.
I have a small GitHub project, FindingJsonCPlusPlus, that illustrates how the property_tree library can be used to generate JSON strings.
For help with JSON in C#, see my post Finding Json for C#; it points to its own associated GitHub project.