If you have already designed your database then you may do one thing that you can host your database in web through Filemaker Instant Web Publish. By which simulttaneously many users can access your database.You can give your url (IP Address:Port Number)/Link to clients so that when they will enter the url/Link, automatically get connects with the database and also you can provide security so that only limited users can access your database. It is very easy to host any database through FMIWP.
Hope it will works correctly.
Dillip Kumar Mahapatra
You could also set up a fileMaker file that uses a script to connect to the hosted database. This sets you up with FileMaker clients instead of the limitations of a web browser, but also requires a full up install of FileMaker on every client machine. (FileMaker Go with an iPhone might also be an alternative here.)