This week's book giveaways are in the Refactoring and Agile forums. We're giving away four copies each of Re-engineering Legacy Software and Docker in Action and have the authors on-line! See this thread and this one for details.
First of all, do you know what namespaces are used for in XML and how they are commonly used? Probably not, most people don't really understand them. So I would suggest you read a tutorial about namespaces. I am not impressed by the w3schools tutorial, they are quite superficial. The namespace tutorial at zvon.org is more thorough.
When you have done that, I found this paper on how to use namespaces in schemas that looks like it goes through how to configure things quite well.