I think the first song I learned was Baba O'Reilly by the Who. I never learned it completely, though, because I don't really like the song.

Black Sabbath is a little easier than that Metallica song, imho. You can work on the rhythms and work your way up to the solos. The We Sold Our Soul for Rock-N-Roll tab book is fun to play.

If you want to start with Metallica, the Kill 'Em All tab book is their easiest to me. Seek and Destroy is pretty cool and fun to play.