I recently posted several bits of advice regarding what you should study in order to understand how to change the namespace of an existing project. If you take my advice as being sarcasm you'll get no benefit from it. If you take it as sincere advice to help you focus your studies to learn the underlying issues you can come away with more than you thought you could.
If you only care about namespaces you can search for my comments here around a year ago. I went into it in some detail, but my mistake was in assuming that people understood assemblies, metadata, references, and deployment. Because of my mistake, the people who asked about namespaces were not able to make use of my comments. They did understand my words and my analogies, but they didn't have a good fundamental knowledge of .NET.
To be fair, most beginner books do not cover these subjects adequately, so you need to select the books and websites that do.
The book covered in this message forum is aimed aquarely a middle-level developers and there is no attempt to cover the subjects mentioned above. The book would be well over 1000 pages if it attempted to cover all that.
Sometimes you need a strong foundation upon which to build a house. You should not start building merely because you have a hammer and some nails.
I'm sorry if I offended you, but I give the same advice to co-workers, local user groups, and even to my own son who is now learning programming.
If you put some effort into learning the underlying concepts you can ask specific questions about those areas if you need help. Once you understand these things, you can easily change the namespaces, but more importantly, you'll also be able to do a lot more than that!