Homework (This entire paragraph seems to be written in a very reflective manner.  It is as if you are inside your own head.  You seem to be telling this to yourself.  I hope I accurately understood you.  I have suggested changes based on my understanding of your intentions.)

In this moment iI'm doing much a lot of homework,; I have 3 days trying to finish it but I can't.
I have static's homework with thrity six problems about the forces and moments. I'm so tired and stressed, that's why now I'm writting on italki to relax a moment.

No worries Seergio. I often feel the same way.  It is nice to take a break from our work every once in a while.  I can assure you that my Español is worse than your English. Keep working hard.  I am sure you can achieve your dreams!