Meditation is simply putting your mind at ease. Imagine a lake with no ripples, a placid and peaceful body of water. This is what you want your mind to achieve. You want no thoughts to interfere with your peacefulness. Meditation is a way for your mind to take a backseat while your breathing becomes the driver.
Breathing is the key to meditation.
Breathing remains normal. You don't take deep breaths, just relaxed ones. Breathe in and breathe out normally. It sometimes helps to mentally watch your breath going in your nose, filling your lungs and then sweeping down your body and then up and out through the nose again. Slow and quiet breaths will help you achieve a quiet and relaxed state.