Simplest way is to turn on network sharing.
Best way is to host the file on FileMaker server.
Runtimes are self contained units and can not be shared.
As Kris mentions, your mention of runtime is a bit worrying, those can not be shared.
so everyone needs a copy of FileMaker Pro. Do *NOT* use OS-level file sharing; so do not put the file in a shared folder and let people find it through Windows Explorer or the Finder.
There is a limit to the kind of sharing you can do with just plain FileMaker Pro/Advanced as the host (max 5 guests). That also has other limitations, namely that FileMaker Pro is a desktop application, not a server process so host has to have the files open at all times before other people can get to the files. And there are no live backups.
All of these limitations go away when you use FileMaker Server.