reduce white space between navigation bar and page content

Are you using a child theme or a custom CSS plugin?

how do i know that?

Try looking in Appearance -> Themes for your currently active theme?

This is all I see:

Current Theme
Bronxville Wellness

By the WordPress team
Version 1.2

The 2011 theme for WordPress is sophisticated, lightweight, and adaptable. Make it yours with a custom menu, header image, and background — then go further with available theme options for light or dark color scheme, custom link colors, and three layout choices. Twenty Eleven comes equipped with a Showcase page template that transforms your front page into a showcase to show off your best content, widget support galore (sidebar, three footer areas, and a Showcase page widget area), and a custom “Ephemera” widget to display your Aside, Link, Quote, or Status posts. Included are styles for print and for the admin editor, support for featured images (as custom header images on posts and pages and as large images on featured “sticky” posts), and special styles for six different post formats.

So you are not using the Oh theme. Looks like you are using a custom theme (your theme was not created by the WP team – although it appears to have been based upon one that was). Who created this theme for you?

A consultant did it.

I think you need to go back to whoever created the theme for you and ask them for assistance. The only other options would be to start learning CSS:
CSS Tutorials
Learning CSS

ok, thanks so much!!