another way you can learn is position yourself on the box as if you were doing a boardslide (just stand on the box with your board straped on your feet). then have someone pull you forward to learn how to slide on the board and balance yourself. you can hold onto ski poles in front of you and have two people pull u from each side. Just do it when there is noone around.
Yeah, the problem that you are having isn't tune related. But don't listen to anyone who says don't detune for jibbing. Because once you correct the problem and keep the base flat, if your edges are sharp, they'll catch, and throw you the other direction...onto your face. See my instructions above.