Here's a simple vid from Mike at informedtrades.com that gives you an insight.
If you prefer to learn from the man who invented Bollinger Bands then I suggest you pickup a copy of his book or visit his site at bollingeronbollingerbands.com. Have added this to my reading list. Johns contribution to technical analysis is globally renowned and his book has been translated into 8 different languages. Quite tempted to pickup his DVD seminar as well, but will see how I get on with the book first.