How do i go about centering my menu?

sorry if this is mega simple!

Look in the theme options for Configure Header Area.

blimey. that was easy. i didn't put the two together - thank you.

how do i center the logo and header so that they are aligned with the menu?

Use CSS in the Logo Area Styling and/Or Logo Image Styling boxes depending on your situation. To center you can use the [margin: 0 auto] along with a width CSS to center.