For three users (up to 5 at one time) you can publish to the web from FileMaker and your users can use a web browser to access the database. The devil is in the details. The file and Filemaker must be configured correctly. You will also need to set up port forwarding on your internet router so that your other users can access your database by connecting to the router's IP with it then forwarding it to your host computer.
I can describe in general, but you'll need to research the details. The FileMaker side of this is documented in a PDF document installed with your copy of FileMaker and which can be downloaded from the Downloads link at the top of this screen.
The port forwarding details are specific to your Internet Router so you'll need to research those details from other sources. I understand that there are several sites on Port Forwarding you can find via a web search that provide detailed info specific to different Internet Routers.
And yes, there are a number of companies that will gladly host your filemaker database for you if you'd rather go with that option.
Thanks, I understand the concepts. I am a little nervous about establishing the gateways to my home computer network.
However, if i go with the hosting idea, see if this concept is correct. The database will reside on the internet server. i establish a VPN to the server that can access the DB. Do the same for 2 other people. Done. Correct?
I don't think you'll need VPN for this. The other users will just need the URL to the hosted site so that they can use their browser to get to it. You might contact a few of the hosting companies that provide this for the technical specifics on how to set this up with their service.