There isn't a REAL easy way. If there are several rooms with ethernet ports, then they probably go to a central location. It could be a closet, the basement, attic, or even outside. Other services such as phone and TV coax may also go to the same area -- this is called home run wiring.
They may terminate inside a metal or plastic wall box (12in x 12in or larger).
Once you locate a group of wires then we may be able to help you locate a specific wire.