Attachment links in Campaigns

Attachment links in Campaigns

I see lots of articles that say this can be done, but not any that actually show me how to do it.  I tried to chat this morning and was sent a link, but I tried to follow it.  I just get in a loop.  I don't know how to place my tinyurl in the document.  I don't want to put in libraries as it won't be used again.