So if I got that correctly, there is not 1 header file for that library but alot of em. Well, first I'd have to say that's a bad structuration the maker of the library did. Every library shouldn't have more than one header file (if that header file includes other files is another thing ).
I see no other solution than you make your own single-included header for that library. Try to compile, see what "undeclared identifer" you get then search for that header file and include it.
The header you make could look something like this:
Make sure you use the #ifndef / #define if you include the header in more than one file in your project.