I have the ab lounge and I have two questions.?!

I have the ab lounge and I have two questions.?

I am 12 years old 5,4 and about 105 lbs.
I was wondering how many ups and downs on the ab lounge I should do?
30 is no problem for me.
Also, I know the ab lounge makes your abs look better but does it any way make you look skinnier any other way?
I'm not that fat in my stomach.
Well, the BMI scale says I'm underweight a little bit but I don't think.
Think you can answer my two questions?

Ab exercises do not remove fat from your belly. Only losing overall body fat will allow you to lose belly fat. Ab exercises build muscle, that's all. The commercials are blantanly deceptive.