Spotify Authentication with C++

I am trying to get an Authorization code (if that is what it is even called) from Spotify's Web API using the C++ Rest SDK. I have a good background in C++ but very little when it comes to anything web-based and I have no idea how to go about this kind of authorization.

Does anyone know how to go about this or have useful links on these topics? I have looked at cpprestsdk's "Getting Started Tutorial" and somewhat understand it, but any help (or code) on the topic would be greatly appreciated.