You skipped the store-bought stuff in an attempt to make your own crust from scratch, but the dough won't stop breaking apart when you try to roll it out. What should you do?
If the pastry is crumbly and difficult to roll, then the crust is most likely too dry. Adding moisture will help the dough become more coherent.
Add a few sprinkles of cold water (no more than a teaspoon at a time), handling the dough as little as possible until it's evenly moistened. Is the dough cracking only a tiny bit at the edges? If so, it simply needs to warm up a little bit — but not too much, otherwise the crust won't come out flaky.