Web designers, how do you work (and sync files) on two computers at once?

Hi all. So, I’m doing a website or two. I was using Dropbox to keep my files in sync between my Mac and PC. However, I’ve come to the conclusion that’s actually a very bad setup. Updated pages and images weren’t showing up promptly, or at all. So, I’m looking for a setup/workflow where I can jump and edit between computers. (I use Dreamweaver if that helps or hinders the workflow.)
I’m below novice if I were to setup some sort of local network, but I’m open to anything.
Thanks!