Answer:
depends on the model. exactly like a Halloween mask so you can see out of the eye holes. there are probably straps in the back that go around your head. tighten these. there should now be a seal around your face. breath in and out of the mask. if all the air enters through the filter and exits through the release valve, then you got it right. if the air comes in from other sides, you should re-check the seal. make sure your hair isn't in the mask and that it is tight enough.