Hey and welcome to SFML, newcomer!
In order to use SFML, you need to have a fluent understanding of C++ first. Then, you can read the SFML tutorials
here.
Use the Getting Started tutorial that corresponds to you and then move down the list, skipping Using OpenGL and Integrating tutorials and maybe the Network Package.
Note that, although SFML can certainly be used to make a Risk-like game, there is no tutorial that will teach you the advanced concepts of engineering one.
Rather, the tutorials will teach you the basics, leaving it up to you to connect this basic functionality together with your own code to achieve something far more advanced.
If you are looking to get started on a game right away, while skipping all the core of it, perhaps using a game engine would be better for you.
