1) Type the text of the link into the body of the node.
2) Go to the "File Attachment" section, click Browse, and select the document on your computer you would like to link to.
3) Click "Submit"
4) Click the "Edit" tab and copy the address of the document shown in the "File Attachments" section.
5) Select the text of the link in the body, click the "Add Link" icon ("chain") and paste in the copied address.
6) Click "Submit".