Is the goal to build the actual workings of the app (you want to learn CRUD app development)? Or do you have a product/service that you want to sell using the app (e.g. you want people to be able to create an account and buy and sell).
In the first case just search for tutorials or best practices on building apps. For the second case, just use an off the shelf application.
In the first case just search for tutorials or best practices on building apps. For the second case, just use an off the shelf application.