Please read the manual before posting. You can find the manual here: http://box2d.org/documentation.html
Please don't use private messages or send me email to ask me questions about Box2D usage. I created these forums to share information and PMs don't share information. You may use PMs to inform me of site issues or for questions that are not of general interest. Please use your best judgement.
Read the FAQ
Here the FAQ: http://code.google.com/p/box2d/w/list
. Please read it.
The distribution of Box2D includes an API document generated with Doxygen.
The distribution of Box2D also includes and extensive testbed with many examples of Box2D usage.
I hope you will read the manual, the FAQ, the API docs, and the examples in the testbed. I know it is a lot to digest, but hopefully it will also be rewarding. After that, please post any further questions you have to this forum. Don't hold back, because many people can benefit from the exchange.
Before you Post
Please check your code thoroughly before posting about problems. Try to be sure the issue is in Box2D and not due to other parts of your code. Please read the documentation related to the problem to see if there is an existing solution.
If you want help with Box2D, please make a post like the following: http://box2d.org/forum/viewtopic.php?f=4&t=4872
Notice that the poster clearly spelled out the problem and included code for the C++ testbed. This is the surest way that you will get effective help. You can now generate C++ code automatically using the b2World::Dump command.
Box2D has one of the best, most helpful forums on the internet. Please lets keep it that way. Please give people the benefit of the doubt and give them the respect you would want to receive.