Create the line of text or image you want to to be a clickable link.
After the image is clicked or the text is highlighted, click the link button.
click the [Upload] tab, then hit the [Choose File] button.
Find the file on your computer.
The hit the [Send to Server] button.
The dialog box should automatically switch to the [Link Info] tab and populate the link.
Now just hit [OK].
P.S. - with PDFs it's a good idea to select 'New Window' in the [Target] tab as well, so people can stay on the same page while the PDF opens in another tab.
