Read thoroughly the wMTN_GettingStarted.pdf. It describes how to set things up completely in TN and in IS.
You’re only partially finished with TN setup, based on what you’ve described.
The next step is to define document types within TN. This allows TN to do document recognition for you. Most often, XML docs are recognized by the root tag but you can specify a number of things to configure TN–e.g. presence of a tag within the doc, the value of a data element, etc. Doc recognition will also “pull out” attributes so they can be evaluated by the processing rules.
After that, you need to specify processing rules. A rule can execute its action(s) based on doc type, doc attributes, the sender, the receiver, etc. The action can be execute an IS service, deliver the document to a partner, send an e-mail, etc.
This is a very high-level explanation. As I mentioned earlier you really need to familiarize yourself fully with the TN documentation and try out an example or two. Of course feel free to post any specific questions you might have–someone here will undoubtedly have run across the situation before.