Tutorial
If you would like to create your own RealAudio and RealVideo files, you will need a RealEncoder. There are several encoders available for free from RealNetworks:
The RealEncoder 5.1 - For Windows 95/98/NT, Mac OS 7.x, Irix 6.3, SunOS 5.5.1, Solaris 2.5.1
The RealEncoder G2 Beta 2 - Available for Windows 95/98/NT only.
RealSystem G2 Authoring kit - A complete resource for building multimedia presentations in RealSystem G2 - Note that some of the files produced by the RealSystem G2 Authoring Kit will not work unless you have access to a RealServer G2. (which you do not have at Geocities)
RealMedia Plug-in for Front Page - The RealMedia Plug-in is an add-on application to Microsoft® FrontPage® for creating streaming media enabled web pages. The RealMedia Plug-in works in conjunction with a RealEncoder
It is important to note that Geocities does not employ RealServers but this will not stop you from putting streaming media on your web pages. Just be sure when using your RealEncoder that you select for the options that do not require a RealServer. In the RealEncoder 5.1, this means selecting the "Destination" of "file" and in the RealEncoder G2 that you select for "Single Rate".
A more complete discussion of using the RealEncoder is planned here for the near future.
This Encoder is the one I use because the files produced are "playable" by all versions of RealAudio players. The G2 encoders are still beta releases and I have experienced many problems using them. You have been warned! Use at your own risk!
Be aware that files encoded with the G2 encoder can only be played by G2 players.