At first, put "Yoko-Bue" under your lip looks like this picture.
Is your mouth touching "Uta-Kuchi" bigger hole than other holes on the left side at it ? If you can do so, try to purse up and stretch your lip both end. And Now, puff your breath in "Uta-Kuchi". (Your breath is divided into two direction, which inside and outside it by"Uta-Kuchi".) If the gods are smiling you will hear the tone of japanese flute.
=== NOTICE ===
1. Put your fingers firmly over the holes so the air doesn't leak by.
2. Don't puff out your cheeks.
3. Breathe in deeply and breathe out as longer as you can. (abdominal breathing)