How to transfer songs from itunes to iphone 4s?

I previously had an ipod touch 4th generation that i transferred songs from my computer with itunes to it. I got an iphone 4s and i dont know how to transfer songs from itunes to the iphone4s. I done the add file to library where i copy all the songs from one album and then when i do this, it transfers the entire album to itunes.
However, how do i transfer the songs to the iphone 4s? I dont see an option to do this. Back then with ipod touch, i just dragged the songs to it and then it would copy. I dont see this option nor do i see a sync option.

Are you using a Mac?

ETA: It probably doesn’t matter. Just plug the iPhone in, launch iTunes, and go to “devices”. Select the iPhone, and adjust the sync settings for the music you want to sync.