Click File Manager

Click the public_html folder

Add a New Folder
If you don't already have a folder for your pdf files add one now - if you do skip this step

Click on the new folder (pdf folder )

Click "Upload" - in Top Menu

Drag and Drop your PDF here

Link to the PDF in your Page
This video will show how to link to the pdf on your site page http://screencast.com/t/ZWJiYTg3M