well, you use ip adresses as a connection location, just like localhost is binded to 127.0.0.1 meaning your own machine.. So, if your ip would be 123.123.123.123 (ifconfig will show your ip listed amongst the data of the interface you are using), you could issue on a remote machine:
Code:
ftp 123.123.123.123
As simple as that it is..
You may want to get an ieasier to remember "domain" than your ip address.. Then for eg
http://www.no-ip.com could be to your interest.