Hello
Why Leonardo is unable to load on port 20-23?
Why many Arduino stuff (Leonardo, YUN, GSM) have a random behavior?
John Rossati
Which OS are you using? With Linux, it'll be /dev/ttyACM? with the ? being a number from 0 to god knows. That is, if it's seen! With Windows, once you add the *.inf file, it'll be a COM? with a number from 1 to god knows. With a Mac, you're on your own unless a Mac user finds this. There is a tutorial found on this site for making Leonardos to work with Windows and Macs. With Linux, no driver is supposed to be needed. Just make sure your Linux distro came from the matching official site, not from some place shady like a DVD from a magazine.
Good luck!