These two videos explain everything you will ever need to know about how to breathe for singing. Don’t allow anyone to make it more complicated than the masters of the Old Italian School of Singing gave it to us.
Watch the first video, “Breathing for Singing,” at least once to understand the principles behind it.
Then use the Farinelli Breathing Exercise video daily. It’s the oldest exercise to learn how to breathe for singing, and is still the very best there is!