There is a sync handheld option in the action window in the bottom left. Also when you hook up the ipod the action window will show the ipod contents and you can drag and drop files and playlists into that window.
Having said that, it's my undestanding jriver is 1 step behind iphone with compatability on firmware updates from apple. Apple apparently doesn't like 3rd party software syncing with the iphone so they make it a pain with every new firmware upgrade. If you hook up your ipod and jriver doesn't recognize it this is likely the problem.