There are many places to go to find out more about NServiceBus. Of course, I would be remiss if I did not first mention the official NServiceBus documentation, at http://docs.particular.net.

NServiceBus boasts a very active and user-friendly community. You can find them at the official Particular Software discussion group, at https://groups.google.com/forum/#!forum/particularsoftware.

If you're not in the mood for discussion, Stack Overflow may be a better place to go for any question that needs an answer. Be sure to tag your questions with the nservicebus tag. There are several community members (including me) who use this tag, looking to help out others in need. Also, be sure to read other tagged questions. There's a good chance your question has been asked before at http://stackoverflow.com/tags/nservicebus.

Remember that while NServiceBus is not free, it is still open source software. If you like, you can dive deep into the source code by looking up the NServiceBus GitHub repository...