To use the I Ching, all you need is a copy of the I Ching and three coins that have a heads and a tails side. You will also need a scrap of paper and a writing utensil. Start by holding the coins in your hand, and think of a question you would like answered. When you have a clear idea of the question you would like to ask, throw the coins. Take a look at the results. Each head is worth 3 and each tails is worth 2. So add up the value. For example, suppose you throw the coins and the coins fall as two heads and one tail. That means the total would be 8. 3 + 3 + 2 = 8. So for the first line, you would record an 8. Repeat this process five more times, writing the numerical values in a vertical sequence from bottom to top. Once you have these 6 numerical values, you are ready to begin building your hexagram.
To build a hexagram, you're going to simply write a broken line for each even value, and a solid line for each odd value. Once you have 6 lines, you have made a hexagram. When your hexagram is formed, you must now look it up in your copy of the I Ching. Usually on the very last page of your I Ching there will be a chart that makes looking up the hexagram easy. When you find your hexagram, read the chapter of the I Ching that corresponds to the hexagram.
Take a look at your hexagram. Do you have any sixes or nines? If so you will need to read the text under the line that is either six or nine. Usually this will be written in your I Ching as first line, second line, etc., or in some cases it will be described as first six, second nine, and so on. These are known as the changing lines. The text that is in this section pertains specifically to you and your question. Now you will make a second hexagram.
For the second hexagram you will need to change all of the lines with a six to nine, and all the lines with a nine to a six. Leave the rest of the lines the same. Then look up the resulting hexagram in the same way you did the first time, including the six and nine lines. Finally, after you have done all this, you will then 'check your work' using the rtcm (retrospective three coin method). This is a method that I learned about by reading a book by Carol Anthony, who is a leading writer on the subject of the I Ching. To use this method, simply form a theory about what you think the I Ching is trying to tell you. When you have a theory, hold it in your mind and toss the coins. If you get three heads, it means yes. Three tails is no. Two heads is yes, but … and two tails is no, but … keep doing this until you get a clear idea of what the I Ching is telling you. When you ask it if a particular interpretation of the reading is correct, toss the coins, and they are all three heads up, you will know that you have hit on a correct interpretation.