First, on your 'Media library' page, you need to change the status of your files to 'Public'. Click the edit button beside each file to make the change.

Once that's done go to the edit page for your profile or ad. Near the bottom of that page under the heading 'Attachment' you will see a list of the files you made public. Tick the box next to the ones you want to show on the bottom of your public ad or profile page. Now click the 'Submit changes' button.