QUOTE(jennthesaxplayer @ Jul 19 2007, 03:19 PM)

Ok I have two different lines of music on one stave, in one bar. Both the tails are downwards though

Klarinetten in A means Clarinets in A, 1 2 means there are 2 of them. If you look at bar 13 and 14 (the bars you were asking about in the transposition threads you started) you'll see that some of the notes have stems down, and some have stems up. Clarinet 1 plays the notes with stems up, Clarinet 2 plays those with stems down. "a 2" means both of them play in unison (bars 9, 11 and 12), if there are two notes on the stave (bar 10) with the the stems down, one clarinet will play the bottom note, the other will play the top note.
The AB Guide to Music Theory has a Glossary at the end of part 1 which has meanings of these words - it really would be worth getting it.