You will need to be more specific with your question. I'm going to assume you are talking about an Ethernet router (not a wood-shaping router). The first place to start is with the manufacturers users guide/manual. Nearly all manufacturers put a copy of the users guide on the CD that is included with the router. If you don't have that, they are also usually available at the manufacturers website.
Is there something you are specifically trying to do that is giving you trouble?
Please post again with more details. It would be good to list the manufacturer and model number as well.