How Do I link to pdf documents?

Since I can't get teachers to visit my website, I thought I would post links to several pdf files directly on teachers/gradebook/home. I tried storing the pdfs in the custom folder for teachers/gradebook, but I'm not sure how to reference the page.

For example:
For info on how to setup your gradebook, [a href="/teachers/gradebook/filename.pdf"] click here .
(I intentionally used [ ] in my example instead of < > so that you could view the code.)

This returns an error of "The file is damaged and could not be repaired." Is this even looking in the custom folder? Or should the pdf be stored somewhere else? My knowledge of html is pretty rudimentary, so I'd appreciate any direction you could give.

Carol