Okay, here's the thing.
You come here asking for help with your English, but you ask for help with your "letta"? That shows that you're not taking your writing seriously.
Your letter has a run-on sentence. Worse, it makes no effort to say why I should hire you. What do you offer me? Why are you a match for the position I have open? What will you contribute to my business?
A cover letter explains why you would be a good candidate. It doesn't just say that you want to work for them - obviously you do, or you wouldn't be writing.
I think you might want to google "Cover letters" or look on monster.com or careerbuilder.com for some pointers.