Sorry for the late reply,
Box2D.XNA can be a great technology to use in many different kinds of 2D games. If you are new to game development in general, I would recommend starting out by making games that do not require a physics engine. Integrating a 2D phyics engine
into a game (especially into the game mechanics) can be tough especially if you haven't dealt with the basics before.
So, if you are new to game development I would start with some of the XNA tutorials or starter kits:
http://creators.xna.com/en-US/education/starterkits/ There is a lot of other info and an excellent forum on that site.
If you are familiar with 2D game development already and just want to incorporate physics, particularly Box2D.XNA, then you could start here:
It isn't much but it can help you jump in to things. The best way to learn is to experiment and play around with the testbed samples provided in the Box2D.XNA solution.