Hi Ron,
I’m always happy to help new cooks! There are a lot of ways to make a crumb topping, sometimes called streusel, but the standard streusel is made by combining 1/2 cup brown sugar and 1/3 cup flour in a bowl. Then “cut in” 1/4 cup (4 tablespoons) butter. To “cut in” the butter means to take a pastry blender or two knives and cut up the butter (in the bowl with the flour and sugar) until the tiny pieces of butter are mixed in with flour and sugar and the whole mixture looks like coarse crumbs. This crumbly topping is sprinkled on the top of a pie or other dessert (or even fresh fruit like peach halves or cut-up apple) and then baked.  You might also want to check out my Streusel-Topped Peaches—it uses granola to create an even crunchier streusel. Hope this helps – let me know if you have more questions!