Transfer mp3 files from Mac to iPhone Music app using iTunes 12.0.1 I have not done this for a while.  The iTunes version 10 or so was quite intuitive to do this task.  The current iTunes version does not seem so obvious anymore.

Any instructions would be appreciated.
Plug your iPhone and click the device icon in the iTunes bar.





Select Music on the left side bar.
From there you can select whatever music you want from you library (by artist, album, etc.).
Select what you want and hit Sync button in the bottom of the screen.