I need to add a library of OAuth. I am working on a app that needs to use OAuth protocols

here is the library in c++

http://liboauth.sourceforge.net/index.html

They have provided all the links and they say that its Qt tested.

I just need to know how this library can be added in the app so that i can call the functions in it

thanks.

P.S. I would also like to know how some important data such as username and password can be stored in a application. should i use a file to write it down in a text file?