Are you signed into the correct ID on the iPad?
Did you select the content to sync in iTunes for the iPad?
Do you have any content restricted in Settings>General>Restrictions?
Connect the iPad to the computer and launch iTunes.
Click on the iPad name on the left side under devices.
Click on the Music Tab on the right.
Click on all of the albums or playlists that you want to sync - or the entire library if you like.
Click on the Sync Music Heading.
Click on Apply in the lower right corner of iTunesDo the same thing for your videos. If you are running iTunes 11 and can't see the sidebar go to View>Show Sidebar in the menu at the top of the screen.