I'm having trouble with breathing support.  I tense up my stomach when singing because it sounds alot better, but I've read you have to relax your stomach?

Good question, Vladimir! Ideally you'll relax the belly to expand as you inhale, but there's engagement of the belly on the exhale (as you sing). That could be felt as flexing, tucking, or slight tensing - so as long as you feel good with what you're doing and aren't experiencing tightness/rigidity, perhaps what you describe as "tensing" is just engaging the abdominals! Feel free to submit a video for feedback if you'd like to demonstrate.