The I-Ching is also known as the Book of Changes and you use Chinese coins (coins have square holes in the centre) to help you build patterns. These patterns are known as hexagrams (hexagrams are a combination of short and long lines, each combination has its own meaning). I tried I-Ching readings many years ago and found these interesting and accurate, though I must say it's not the easiest form of divination.
I've gathered together a selection of links that explain what the I-Ching is and I'll be posting these onto the forum very shortly.