I would probably go with SFML for a starter, or SDL if you want some more advanced functions. There are plenty of c++ graphical libraries out there. A GUI may be more difficult. For a GUI you could use SFGUI (an sfml based GUI system), or use WXWidgets and the windows api instead if you are on windows.
If you just want a GUI, or the GUI is the main part you are focussed on, my recommendation is Qt. It's very powerful, and much nicer to program than WxWidgets or the WinAPI.
As for difficulty... well, in some ways graphics applications can be easier than console applications, once you've learned the framework. You should be fine; just spend time fiddling with things, and look at example programs and the like to see how other people do things.