The billing system source code is now available for download. This program contains advance coding so this is not particularly for beginners. But if you're a newbie and would like to learn from this program you might use the debugging tools built with visual basic 6.0.
Debugging tool was my companion when I started to become a programmer. I downloaded some of the program from the internet and use it to know the function of an application.
Feel free to ask any question. You may also use our forum system so that other can participate and most likely answer your question before I knew it.