To create a link to an externally hosted .pdf file please do the following:
1. Go to Manage Website > Edit Website
2. Create an information page, from where the PDF file should be available
3. Add a Text and Image section to this page, and open it in edit mode
4. Type something like "Click here to see our manual (in the PDF format)" and click on the 'Create link' button (fourth button from the right)
5. In the Add Link window select the 'Enter Internet Address' radio button. Specify the path to the PDF file, e.g. http://www.domainname.com/pdf/Manual.pdf,
in the 'Internet Address' field and click Done.
6. If you go to the newly created page and click on the link, a new browser window with the PDF file will be opened. If you want the link to be opened in the same browser window, please untick the 'Open Link in New Browser Window' check box at step 5.
To upload a .pdf file which is stored locally on your computer, repeat steps 1-4, but after that go to Upload File in the Add Link window. See How to link to a file for more details.