How do I trasfer music from my iTunes library to my iPod?

My cellphone has iTunes, and I can't get the songs that I am downloading onto my library to go on my cellphone (it works the same way as an iPod though). What do I do?How do I trasfer music from my iTunes library to my iPod?
hit import as soon as u get the songs on ur library then plug ur ipod into wherever u have to then hit import. it will import all of your songs, i think, i only use my pc for downloading songs on my ipod!!!