Are you not syncing your phone with iTunes? It will sync the content you set it to sync when the phone is connected to the computer and iTunes is running. Since this is an iPhone question it should be in the iPhone forum not the ATV fourm.
This site contains user submitted content, comments and opinions and is for informational purposes only.
Apple disclaims any and all liability for the acts, omissions and conduct of any third parties in connection with or related to your use of the site.