You can find basic information about user identification at the University of Münster, that you need for any login in computer systems, here.
How you can use the NWZ with your user identification, you can findhere.
You can use some services only in the computer network of the university and not from home for example. If you want to, you can use a so called virtual private network (VPN) to add you device to the university network and use the services.
In most of the university buildings you can access a wireless network with your notebook, tablet or smartphone. By the way, this works via the eduroam-project on most colleges in Europe.