The first step to learning how to speed read is to understand the process behind it. When you speed read, you are actually re-training your brain to process the words that you are reading differently than you typically do. Instead of reading from left to right, you are going to train yourself to read from top to bottom, decreasing the time that it takes to read.
To begin training, you should re-format some of your reading material to read straight down, with only two or three words on each line, as opposed to regular across reading, from left to right. Begin reading your material this way; while it will seem awkward at first, it will feel more natural with practice.
Once you are able to read from top to bottom easily and comprehend what you are reading, you need to begin training yourself to move your eyes from left to right as little as possible when you read full, normal print. You do this by gradually increasing the amount of words per line as you continue to limit your left to right eye movements.
Practice this technique until you feel comfortable with it before attempting to read regular print materials in this manner. Your comprehension may decrease as your brain gets used to this new way of processing words, but over time, you will become more proficient at this reading technique and it will become second nature to you. Your comprehension will increase and so will your speed.
For additional practice, you may want to purchase an online speed reading course or order a speed reading program which will have pre-formatted materials for you to read and train with.