All the translations will tell you how this works - it's absurdly simple. When you consult the I Ching, you build up a hexagram line by line according to the results of coin tosses or one of the other methods, such as sorting yarrow sticks or pulling marbles from a bag. These are the 64 hexagrams, which means simply a pile of six lines, either broken or solid.
The I Ching as you buy it today will be a collection of texts - a wonderful mixture of imagery and advice, philosophy and poetry - divided into 64 'chapters'. There are so many ways to answer this one! The I Ching is the world's oldest oracle it's a book of Chinese wisdom it's the accumulated experience of over 2,500 years of diviners and sages, and beyond that of unimaginably ancient oral traditions it's the voice that has been offering people help and wise, genial guidance for generations.