It assumes that current navigation is using the Template Tag, wp_list_pages(), to display links to Pages. The trick to displaying both Pages and Categories in a blog navigation header is to make the Categories accessible via a Page.
To display a link to Support Category with other Pages in navigation header we need to install a plugin like Page Links To, Redirect etc.., and create a Page called Support and save that Page.
After that edit Support Page and add a Custom Field with a Key of links_to_target and a Value of the URL for the Support category.
Note: to determine the URL for the Support Category, just visit that Category in your blog and copy the URL in your browser address bar.
If you want the Pages in navigation to appear in a particular order then use the Order field in the Attributes module when editing your Page and set that correctly for each Page with wp_list_pages(), use the ‘sort_column=menu_order’ parameter.