I am so sorry but I am laughing so hard right now...I love people who don't bake much...Kay answered your ? ...you can find it in the spice area of the store.... it is what they usually add baking soda to turn it in to baking powder, so things rise.... it is an acid like vinegar so when you mix it with soda and add liquid you get a chemical reaction that bubbles like baking soda and vinegar hence the "rise"
it also stabilizes egg whites so the don't fall, like in meringue cookies