All of this has been covered. Check the first stickied thread in the beginner section for basics. Check the forum faq section to get started with BT, and see also aircrack-ng's website for more on their product, including basics and tutorials.
Then check the site for grimwep, since this is not really supported in BT4. If you get stuck with an actual problem post what you were trying to do, any errors you may have received and the source of information that you were working from.
Lot's of reading to keep you busy for a while.