The attention you give the different things around you is a spotlight, and all day you move it around and point it at different things, usually without thinking too much about the fact that you're doing this. As you move it around, you point it at everything you give attention to in your life, from your smartphone, to a conversation you're having, to a report you're writing. And a lot of the time, you direct it at more than one thing at a time. Actually, most of the time you do.

Meditation takes that "spotlight" that is your attention and it points it directly at your breath.

So that's all well and good, but what do you do, exactly? Six things.

1. Get comfortable. Open the timer on your phone, and get into an upright and comfortable posture. Dim the lights a bit, or shut them off completely to help you focus better.
2. Start your timer.
3. Bring your attention/focus to your breath. This is what meditation is all about, and this is what makes meditation both difficult and worthwhile. In this third step, close your mouth and focus entirely on your breath as it enters and leaves your nose. You can focus on any element of your breath that you want - from how the air feels as it enters and exists your nose, to how the air feels as you inflate and deflate your lungs, to the sensation under your nose as you breathe in and out, to the sound you make as you breathe. Don't force your breathing here - just breathe naturally and observe your breath without thinking too much about it.
4. Don't think. This is the hard part. Don't analyze your breath; just bring your attention and focus to your breath, without thinking about it or analyzing it.
5. Bring your attention back to your mind when it wanders. And it will. I've been meditating for 3-4 years for 30 minutes a day, and my mind still wanders sometimes. When your mind wanders, and it will, gently bring your attention back to your breath once you realize that your mind has wandered. You may not clue in at first that your mind has started thinking again, but when you do, gently bring your attention back. Don't be hard on yourself during this stage. Just gently bring your attention back.
6. Again, bring your mind back when it wanders. When your mind begins to think, gently bring your attention back to only your breath. When your mind begins to think about how boring meditation is, gently bring your attention back to your breath. When your mind becomes restless, bring in your attention again. Keep doing this until your meditation timer sounds.