Yes, breathing is an important thing to do. Fortunately (hopefully?) it's something you've been doing for several years on your own now.
Unless you have blood pressure issues, I'm going to trust you to breath however you want to during training. Hold it (look up "valsalva maneuver"), exhale while you exert force, or try whistling while you squat (quick learning curve on that one). You'll figure it out as you go.