Q: i bought ipod nano next gen 7 for my grandaughters. how do i transfer music from itune to ipod? i need help.

A convenient way to load music is to set up automatic syncing. 

First, create a playlist in iTunes and put all the songs you want on the iPod on that playlist.  If you are also new to iTunes and need help doing that, please post back.  You said "granddaughters" in the topic title, so if there's more than one iPod, and you want different songs on each iPod, you can create one playlist for each iPod.  Or you can use the same playlist for all of them.

Then, select iPod in iTunes (click the iPod's device button on horizontal bar that goes across iTunes window), to show the iPod's settings screen in iTunes window.  Along left side of window, in the sidebar, under Settings, click Music.  To the right, you see the iPod Music settings screen.

NOTE:  For anyone else reading this, any songs on iPod that are not in your iTunes library (on the computer) will be lost.

At the top of window, checkmark the box for Sync Music.  This turns ON automatic syncing.  Below that, choose the option to sync Selected playlists, artists, albums, and genres.  Below that, under Playlists, find and select (checkmark) the playlist you created with songs for iPod.  At the bottom, click Apply.  iTunes syncs your selection to iPod.  Going forward, update the playlist (add/remove songs).  iPod does not need to be connected.  The next time you connect iPod (or click Sync if already connected), iTunes automatically updates iPod with the same changes.