You may receive more, better replies if you can frame your question inline and not require others to visit a third-party link simply to understand what you are asking. Asking others to read through an online tutorial simply to understand the question will turn away many who may otherwise be able to help.
You seem to be asking two questions, one about a compile error and another about modifying the application behavior. Please include the complete error message along with any relevant information about what you have done to identify the problem. For example, if the error complains about an undefined variable, have you tried to identify where it is, or should be defined?
For modifications to the existing code, it would be most helpful to others if you would reduce the code to a minimum example which shows how it currently works, and how you want to change it.
Please review the
Site FAQ for guidance in posting your questions. Especially, read the link in that page,
How To Ask Questions The Smart Way. The more effort you put into understanding your problem and framing your questions, the better others can help!