Copied this from someone else (not sure from whom) when I couldn't post a link to my single Twitter post, aside from my "welcome myself" one, because it was too long.
To shorten a link, go to bitly | shorten, share and track your links, type/paste your link in the box, click "shorten," and voilà, you get a new, shorter link to use. Not sure how it works, and this is only the most basic usage, but good enough for now.
Comment: I've discovered the joys of Twitter. I'd enjoy indulging, but cannot stand the embarrassment of knowing no one would read what I'd share. Sad me.