Accessing Files Outside of Network

I'm pretty new to Ubuntu and I've installed and been playing with Ubuntu Server on a spare machine.

What I'm looking for is a way to access files outside of my network.

I've set up Samba and VSFTPD, but Samba only works in-network and FTP would have me download any programs or files that I'd like to modify (i.e. I can't open a picture, stream a video, or open modify and save a document).

I've heard about open-source cloud utilities, but I just want to be able to access my files through Explorer rather than going through a web interface.

Is there a way to essentially set up my own NAS on Ubuntu Server or have a program like Samba that points outward?