On the left side navigation panel, click on My Info, My Information, then My File Library

Once opened, you will see  My Files (My Files includes any files you have already uploaded.)

To add a file to your My File Library, click on the Upload a File button. 

Next,Choose the file from your computer and enter an optional name (under 50 characters), and click Open. 

If you receive an error, try making the file name shorter.