The next step is to learn about the class structure by reading all the class descriptions and example programs. Now of course what you want to do will not fit into any of these neat little catagories. However, with a little thought, it should be possible to decide how to combine the techniques together to accomplish just about anything. The class library consists of objects, your program should too.
Objects interact through well defined interfaces.
Dynamically selected interfaces make things easier to change later. Only modify classes directly as a last resort, use inheritence first. Use descriptive variable names, no one likes cryptic programs. Write more code now, while you understand things, rather than later when you don't. Decide which classes you want to use.