One of my favorite authors and speakers, I would like to introduce you to Jon Kabat-Zinn.
While you watch the video, pay close attention to Jon explaining one breath and bringing attention back to that one breath.
The best to approach meditation is to start small and slowly build. You can meditate while sitting quietly, lying in bed before sleep or even while you are working in your garden, doing laundry or dishes. You can meditate for 3 minutes or an hour. There is no predetermined time in which you have to meditate and there is no predetermined way you have to meditate.