I am trying to make a program for the web game Nationstates.net using their api http://www.nationstates.net/pages/api.html and I want to know how do I call that in the program because I want to make a desktop version of the game with a new feature called NSwars to make have conflicts easier and Role play better
Seems to me that what you need is 1) generate the link (that should depend on what your program does) 2) get the web page and 3) parse the xml result. Fortunately for you, libcurl can get step 2, and libxml can solve your problem 3). On libcurl site there is an example to do both: http://curl.haxx.se/libcurl/c/htmltitle.html
I am using Visual Studio 2012 Express for desktop, plus I've added the include directories and lib directories to my project's properties which is how it's done in VS 2012 now it's a user defined thing.