Click the Help menu when the application is open and choose About Program Name . For example, if you are using Netscape you would click the Help menu and choose About Netscape. A window will pop up which provides you with information, including the version number of the program.
The "About" information screen for some programs lists files of different version numbers - just ignore those. The version number for the entire program will be listed somewhere near the top or upper portion of the screen.
Click the Apple menu when the application is open and choose About Program Name. For example, if you are using Netscape Communicator, you would click the Apple menu and choose About Netscape Communicator.