How can I access an external hard drive on an outside network (my parents house)?

Question

I would like to access the music I have saved on their western digital external harddrive. The hard drive is network accessible from their house but I have moved out and need to know how I can access from my own house. They have a linksys router set up as do i. Winamp remote sucks because it only allows for 800 songs to be shared.. Please help