The purpose of meditation is to stop thinking for a time, wait for the fog of thought to thin, and glimpse the spirit within. Controlling the flood of thoughts is very difficult for most people. Beginners can sometimes become very frustrated, but frustration is just another thought, another emotion that gets in the way. The goal is to release all thoughts, quietly, passively.
A common way to begin meditation is to gently focus on one thing so that it becomes more difficult for stray thoughts to enter your mind. I like to start with a breathing meditation.
To begin meditation, find a comfortable position. Sit in a comfortable chair, with your feet flat on the ground. Place your hands in your lap with the palms facing upward. Close your eyes and begin witnessing your breath. Observe the inflow and outflow of your breath without attempting to control it in any way. You may find that your breathing spontaneously gets faster or slower, deeper or shallower, and may even pause for a time. Observe the changes without resistance or anticipation. Whenever your attention drifts away from your breath to a sound in the environment, or a sensation in your body, or a thought in your mind, gently return your awareness to your breathing.
This is the basic mediation. Once a person becomes comfortable with simply sitting quietly and focusing on breathing, I recommend adding a mantra, which creates a mental environment that will allow you to expand your consciousness.