The Breath Mediation I describe here is a practice of directing attention to the breath, staying attentive to the breath, noticing when your attention has wandered and then coming back to the breath.
It is a very simple practice of noticing and can be quite insightful.
I suggest practing for between 15 and 45 minutes (but even 3 minutes or 3 breaths can help).

Start by sitting in your meditation posture
As you become still start to tune in with the sensations of breathing - where ever you notice them.
As best you can stay tuned in with the full journey of each breath.
If you notice you attention has wandered away from the breath try not to be hard on yourself, understand that this is part of the practice. When this happens kindly and gentley redirect your attention back to the breath.

A couple of pointers that can help -
1. try to listen to yourself breathing as well as feeling. This can help sharpen attention a little.
2. pay attention to four parts of the breath - 1. In Breath, 2. Transition Between In and Out, 3. Out Breath & 4. Transition Between Out and In. Practicing being present for each part of the breath will support your practice.