Newbie in need of help

I have been reading all I can find on creating animations and I am starting to understand how they are made....except when I make an animation, its ok with a 2 frame sit but as soon as I start to add even the simple hand flap animation, my figure starts to bounce up and down and at times the arms have rotated 360 degrees, I just dont get what I am doing wrong lol ...anyone else had this problem or know why this is happening?
btw Im using poser 5 (the second life mesh doesnt seem to work right even though I followed every instruction given) so I have been using the poser 2 lo male model...I think this is the only thing now holding me back lol ..suggestions please!

Due to the spline interpolation, things flip out on the changes from the T-pose in frame 1 to the start of your animation in frame 2. Open the Animation Palette and set the keyframes in frame 2 to Break Spline.

excellent thankyou for your help and reply