Can Someone please help me?

im sorta new to flash and all of that, anyway im having a problem with motion tweening some things.
eg. When i animate a stickman, i will move its arm to swing and move at the same time like people do in real life…
However when i tween it, it will go all silly and move up and down instead of moving smoothly to the left or right. can anyone please help me to correct this?
cheers, chrisbigboat:pope: