haha oh is that the title "comedy writting secrets", I think we're talking about the same book, bright yellow cover right?
I read it back in 2003 - 2004, and do agree that it can help.
As others have said, some people are just gonna be more funny, but there ARE things you can do to improve your self. Understanding how and why things are funny, combined with a wild imagination, can certainly give you a little boost in your level of funny.
Also, start improving in other areas of life. Improve your body, social circle, all these things will help you become a better person and give you an ability to be more funny in certain situations. Hanging out with a bunch of outgoing funny people is probably gonna do a lot more for you then a book ever will, kinda like reading about picking up girls and going out there and actually doing it with people that know what they're doing. So make sure you're actually doing plenty of socializing.
But once again, NOTHING wrong with reading a book about it. I know a few guys who have read that book at at least they seemed to understand humor a little bit more afterwards and are able to form some of their own as well. You can also use these skills to work on your own personal stories and work on presenting them in a funnier way. Write down your stories, and then use all the skills from the book to rewrite them but make them sound funnier. Sometimes just emphasizing on different words and rearanging the way you say things and your delivery can make a HUGE difference in how a story comes out. I think the book will not hurt, it may only help you.