ITunes song sync help! Iphone 4s?

I synced my music and it removed all of my songs. I'm fine with that but now how do i add more songs to my iphone playlist from Itunes? It still says sync under songs.

When you open ITunes you will select the device. Under music select which music you want and select sync again. It should bring everything over to your device. Also click and drag the music to the picture of the phone.