Ānāpāna, what is it?
Ānāpāna is the observation of the natural breath as it goes in and out of the nose. Anyone can learn Ānāpāna and use it to train their concentration and mindfulness. Ānāpāna is a training for a strong mind and can often be useful in everyday life, e.g. before a class test (to collect your thoughts); in stressful situations (to keep a clear head) or simply to relax.
Exercise aids for at home
You can find instructions by S.N. Goenka on a ten-minute Ānāpåna meditation in English with a German translation here:
Mediation instructions for home use