I believe you're getting confused about how to reference things when you're working with a subdomain. A few pointers, in no particular order....
Your main domain is http://www.fallingleavesarttour.com. Your subdomain is http://candacehennekens.fallingleavesarttour.com. Note that there is no www on the subdomain.
When you create a subdomain under your main domain, all the files are kept in a folder under your main domain. In this case, that's public_html/candacehennekens. But you shouldn't create links that point to that folder - let the internal redirection take care of it automatically. So, let's say you've got a PDF file at public_html/candacehennekens/whatever.pdf. The URL to access that is http://candacehennekens.fallingleavesarttour.com/whatever.pdf. Note that you don't actually spell out the subfolder location of the file - that's taken care of automatically.
Relative references, as you've discovered, don't need to address this issue at all, of course. But you don't need a leading "/" on them. So, if witchazel.pdf is in the same directory as the page that's calling it, the call is just:
<a href="witchazel.pdf">Click for witchazel</a>
If that file is, instead, stored at public_html/candacehennekens/adobe/witchazel.pdf, and the calling page is directly under the candacehennekens folder, then the link is:
<a href="adobe/witchazel.pdf">Click here for witchazel</a>
Don't use backslashes in URLs. Some servers don't have a problem with that, but others will choke on it.
One other source of confusion - in some places, you refer to witchazel, but in others you've spelled it withchazel!