>. I thought I needed to find a way to reference from the web root, but not sure how. The directory I am in seems to be always appended first before what is placed here.

That's what the / prefix does - it starts the URL path from the root of the website. So a link that points to /MembersOnly/MemberPortal.aspx should work from anyplace in the site. Are you sure that's exactly how the links are rendering on each page? And, for example "MemberPortal.aspx" actually exists in a subfolder named "MembersOnly" (and not in the root)?