Here is how I make this frosting. First dump in some powdered sugar then add about 2 heaping TBSP's of Crisco then pour in a little milk I use skim. Get a butter knife and start to mix. It will be stiff at first add some more sugar and then a little more milk keep stirring with the knife. If you are going to frost a 13 x 9" cake you can start out with about a cup of powdered sugar and a fourth of a cup of crisco. Use the same method adding little milk at a time. I have done this a million times and it always turns out right. This is how my mom made it. If you want chocolate icing add a couple tablespoons of baking cocoa and use hot water for your liquid. Good luck girls.
Also if make too much you keep it in frig in a tightly covered container.