Or you're not sure you are doing it right?
Do you keep thinking about other things while you are trying to "clear your mind"?
First you need to decide what type of meditation you want to do. There are basically two types of meditation - active and passive. Passive meditation is clearing the mind of all thoughts. You can then allow your "inner voice" or "mind eye" to speak to you. Passive meditation is good for reducing stress, increasing creativity, or just getting in some quiet time.
Active meditation is when you keep your mind active by working on a particular problem in your life or focusing on accomplishing certain goals you have set. Using affirmations while meditating are particularly helpful in this area.
There are many simple techniques to help you meditate. You may have read about them already. They include breathing techniques, repeating mantras, sitting up so you don't fall asleep and visualizing certain objects. These are all good techniques and will help you accomplish reaching that alpha brain wave level necessary for meditation.
However, for a beginner, it can be frustrating, especially if you are not sure that you are reaching the alpha level. There are tools available that can help you. The easiest way to get started is with guided meditation cads. These recordings may have background music or binaural beats designed to help your brain get to the alpha level. Most of them will have a relaxation exercise. These are useful for passive meditation.