Welcome Happystitcher. Ruler folding is generally done with yardage, not fat quarters. When you buy fabric yardage it is folded in half lengthwise with selvedges together. Fold it lengthwise again by bringing the center (folded) edge to the selvedges. Now lay your ruler across the end of the fabric and begin rolling the ruler with the fabric on it. Remove the ruler and store your fabric in the way that is best for you. I used to put mine on edge in dresser drawers. Now I stand them on shelves. Some use plastic bins. The point is that you can see the edges of your fabric so you know what you have, and you just unroll the amount that you need (like in the fabric shop) when you are ready to use it.