Navegation Menu Center – Side text margin

Hello, I would like to position my primary menu of the Catch Base Theme in the center. I have already centered my logo and I would like to do the same with the navegation menu. How could I do it? I also would like to delete the margins of the website for the text. Is it possible to make that the text goes from one side of the page to the other? Now it has big margins on the left and the right side. Thank you! Best regards, Rebecca