How to breath properly?

Breathe into your stomach, you should feel your upper stomach (where the diaphragm is) expanding and the chest should move very little, shoulders shouldn't move at
>mouth breathing
If you're not consciously breathing it should be all through the nose and your mouth should be closed.

It sounds like you're doing fine desu. While there is a lot of talk about breathing into your stomach or into your back etc it is imposible to control where in your body the air is going, and thinking like this more often than not results in tensing in the place you focus on. It is easy to overdo breathing, putting restrictions on yourself like not moving your shoulders etc, but if you take a rich full breath it is necessary for the upper body to swell. Shoulders and chest rising slightly (without tensing them of course) might actually be necessary for a full, relaxed breath.

Lungs are basically balloons, expaning all over when filled with air.

Walk into your nearest United Methodist church on a Thursday at around 5 pm. Sometime over the next two hours the choir is almost certain to arrive for practice. Approach their inevitably slightly homosexual choir director and explain that you are looking for assistance in taking full, deep breaths. They can help, the breaths you take to sing well are pretty much exactly the same as for good, rich workouts, and singers have codified methods and explanations that get noobs to take them well.