Methinks that was an unfair reply.
You can successfully use Linux and ignore network settings for a long time; well until they cause problems.
So whatever distro ure on: look in Network settings.
Not knowing your system I'll have to say use the network wizard thingys.
Remove ethx thru ethy you don't want.
But yes. After a second thought. Knowing ure distro would help if you want command line help.