Problems with iTunes on a new Macbook

I recently switched from a PC to a Macbook AIr. So far everything has been going well except for that I'm having two big problems with iTunes. The first is that only the songs I have purchased on iTunes showed up on the new computer. The songs I imported from CDs as well as all my playlists have vanished. The second problem is that everytime I try to watch a tv show or movie that i previously purchased on iTunes i just get a black screen that seems to be loading. However the show or movie never starts. This is very frustrating and I was just hoping that maybe somebody had this problem before and would have some tips about how to fix these problems. Help!