While I advocate learning by doing for a philosophy and mindset, I also suggest you do some reading as its pretty easy to damage things should you not quite understand what it is you are typing.
Its not something to get scared about, but rather to understand before jumping headlong into things.
The RedHat Linux 9 Bible book by Wiley Publishing
is a great place to start. One cannot survive the use of linux without reading man pages, learn to enjoy investigation. (this book series helped me get going)