Finely grate the piece of ginger into a small bowl. Squeeze as much of its juice as you can into the (store bought) gingerale (hopefully a brand with no preservatives), using a fine strainer, cheesecloth, small, cotton (reuseable) teabag or simply your hand. Adjust quantities to personal taste as it is a very strong herb; a little goes a long way! Dont worry if a little pulp gets into the mix; its good for you! For a quicker glass of Ginger Gingerale, simply chew a thin slice of ginger as you drink your gingerale! Gingerale bought in the supermarkets today have very little real ginger in them and I have found this to be a delicious and effective way for settling an upset stomach.