Breathe in through your mouth and exhale through your nose simply by opening your mouth wide. Then taking a deep breath in, then close your mouth to hold the breath, and then slowly exhale through your nose.
Once you’ve exhaled all continue to do this again. If you are still familiar with breathing through the nose, you can use your nose to hold your breath tightly and release to exhale. Repeat the gesture several times, you will get used to not breathing through your nose anymore.
Learn how to squeeze in through your mouth, hold your breath, and then breathe out both your nose and mouth at once. At the same way, but when you breathe in through your mouth, practice holding your breath for a while. They will help you be able to breathe underwater without too much effort. Repeat many times you will get used to this method.
After learning how to breathe in the air, you begin to learn to breathe underwater with a small basin of water. Fill the basin up to the bottom with water and place it above the waist for your body.
After that, stand upright, take a deep breath in the same way as you took the breath above and place your face into the basin of water, and breathe slowly out through your nose first and then out through your mouth. When you see a nose without bubbles appear and find you can not hold your breath, lift your face up from the basin of relaxing water and take a breath again.
You can close your eyes and do it if you cannot open them yet. In this way, the nose, mouth and face automatically become accustomed to the water environment, do not feel afraid of water and can hold steam for longer. You’re familiar with how to breathe in the air, so learning to breathe underwater like this can be a bit difficult.