Select a blade of grass. Not so thin and not so wide blades work best, but it also needs to be flat and not rounded. Very wide and folded leaves are not the most suitable. In other words, look for a medium-sized blade. Stems do not work for our purpose.
Hold the sheet with the tips of your thumbs. With your thumbs slightly bent, press the base of your thumbs together to hold the other end between them.
Carefully move your thumbs away and get the blade to tension. If you pull it too hard, it will come loose and you will have to start all over again.
Place your lips as if to give a kiss, place them close to your thumbs and blow so that the air goes through your thumbs and over the blade of grass. This will achieve the sound we are looking for.
Don't give up, you may not get the sound on the first try. Try loosening or tightening the blade of grass. This may take them a little time to practice.