Doing my best is what?

I don't know doing my best,but if I think that I don't do my best , I don't do my best,,,. I should do my best now. I am very stupid, but I experience preasure time. I will do my best now,,,I will do my best now,,,but Can I do my best now? It is difficult,,,. If I try to do my best, my face became anger. It ashame myself. I am afraid to do my best. What should I do? I will do my best to make my face that become anger if I try to do my best to calm. It is very stupid, but I do my best about that. Thank you.