Virtual Studio Technology, or "VST," is an audio synthesizer and audio effects program from Steinberg, a music-based software company out of Germany. VST plug-ins are available for a wide array of devices on your computer, including Windows Media Player. Because Windows Media Player is not a VST-compatible host, plug-ins for the platform are basic and allow for little more than audio playback.
Double-click on the VST plug-in installer icon and follow the instructions to install. Because the installer looks for your Windows Media Player folder, you only have to agree with their terms of service and click "Install."
Open Windows Media Player and right-click on the top bar near the "Play, Burn, Sync" tabs. Select "Open" from the list of options to bring up the Windows Explorer window.
Select the .vst file you wish to open. Once selected, click "Open" to open it in Windows Media Player. When the file opens, the plug-in will run automatically.
To edit VST files, use a program that is VST-compatible, such as Audacity, ACID Pro or Reason.