Okay I made the change but it goes out left and right.
Is this not what you wanted when you asked:
The Nav bar is in the middle but now how can I spread the menu bar over the length?
I apologize if I misunderstood. If you want your nav menu to be across the entire page, there is no need to center it. It will take more complicated CSS.
adds padding to each side of the content area: top, right, bottom, and left. To add it only to the sides you may write it in either of two ways.
or in 'shortcut' mode (2 methods do the same thing, second is just shorter to write):
padding: 0 175px 0 175px;
padding: 0 175px;
Removing the padding from the top will remove the 'now taller there where the logo will come in'