You need to make your machine available to your external IP address, usually via the port forwarding setup in your local router.
Alternately, you may want to consider a FileMaker Hosting provider like ourselves:
Thanks for the response. When you say "You need to make your machine available" do you mean the I-Mac that is hosting the database?
Your router or your Cable / DSL modem has an internet IP Address.
You can find out what it is at http://whatismyipaddress.com
This internet IP address can be STATIC or DYNAMIC (you pay more for STATIC)
Your router or your Cable / DSL modem assigns Local IP Addresses to your computers (by default)
NOTE this number can be assigned manually, but most users do not do this.
You can find this in you networking setup control panel or preference.
In Windows XP/2k/2k3 go to: START>Programs>Accessories>Comand Prompt and type: ipconfig
In Mac OSX open System Preferences and open Network, select the Ethernet or Airport option on the left.
If someone sends a request to your Internet IP Address, it will not work because your router is not running FMP
Your router needs to forward that request to the one computer on your network that IS running FMP
This is done by forwarding the Filemaker port request to the proper computer. This is done in the built in webpage on your router.
To find the instructions for this go to http://portforward.com
Select your router in the long list at the bottom of this page.
Skip the ad by clicking Skip the Advertisement at the top right of the page.
Select your application in the long list on this page.
You wll now have a graphic howto on how to set up Port Forwarding in your router.
You send your Internet IP Address to the other person, and the Filemaker request will go to your FMP computer.