Center Pages

Hello! I'm having two different issues with my website. The first is getting my pages to center on the screen. I believe this issue may be related to an adjustment I made to the width of the primary sidebar on the right side of the screen in order to accommodate the widgets I have appearing on my posts pages. I want the post pages to stay as they are, I would only like to adjust the homepage, and about pages. The second issue I'm having is getting the primary sidebar with my selected widgets to appear on the "Food" archive. It appears on both the "Travel" and "Life" archives. All help is much appreciated! Thank you!!