As someone who is pretty much a newbie at this, I only started about a month or two ago. I suggest you take a look at the wiki and stickies here as well. I'd also get familiar with WoW's macro system as you will be making a lot of macro's even if you go through the ISBoxer wizard.
The first few levels will be very easy, it starts to get harder after that. I suggest once you hit 19 or 20 to try and instance and start exposing yourself. You will learn a lot from it and it will help you develop some better macro's. Instance runs for me were great in finding the macros that were very inefficient.
Also don't get discouraged by the difficulty you will get better at it. Once you read outland try some of the instances there, they are a real challenge to run with some of the fight mechanics making it very interesting to box. You will loose time leveling, but will gain a lot of experience in the process.