Setting up Sites on Snow Leopard to share files

Short Version: I need help setting up the Sites permissions so I can dump folders into the Sites folder that someone out of my network can access. When I turn on Web sharing, they can see the main site but they can't see any folders within a public_html folder that I created in the sites folder. They receive an error that says: "Hmmm... can't reach this page."

Can someone help me with information about permissions so I can put a folder in the sites folder, send a direct URL to a colleague, who can then download contents from that folder?

Longer version:

I have an old iMac running Snow Leopard. I use the computer for file transfers. Most options no longer work because the older browsers won't link to sharing options (e.g., Google Drive or Wetransfer). My last good option ran its course last week. I tried getting CrushFTP to work, which is what I used before file sharing sites became an option. But I am having a hard time configuring the program. My ISP has changed and my modem/router setup has changed since I last used CrushFTP. It looks like using the Sites folder is the way to go, but as I noted in the "short version" above, what I can see on my local network when web sharing is turned on is not replicated when someone outside my network tries to access the folder.

I have some tech skills but some of the coding stuff I see online about sites is beyond me. If I know exactly what to type into Terminal, I can do that. Thanks.