First, you need a way to know your dynamic ip.  DYNDNS is probably what you want there.  Or scripts on your home machine to email you whenever the ip address changes, or something.  (google for dynamic dns: http://www.google.com/url?sa=t&rct=j&q=dynamic%20dns&source=web&cd=1&ved=0CF8QFjAA&url=http%3A%2F%2Fen.wikipedia.org%2Fwiki%2FDynamic_DNS&ei=E9oqUNSwJKazigKx44CoDg&usg=AFQjCNHmZFYaxBiTegkz4DtZfZ87o2OGgg&cad=rja AS AN EXAMPLE)

Then, ssh or scp to the machine, assuming you allow those ports to the world, which probably is not a great idea.  Others can surely give a more secure approach!

Rusty

let's say I'm at starbucks and I need a file off of the computer at the house. Please, how do I do it?

condition- I do not have a static ipaddress.
:-)~MIKE~(-: