The sound effect should be Wave (PCM) system. In other words, a format that is capable of playing WAV or using other plug-ins.
The sound effect playback uses three tags: [playse], [stopse] and [ws] basically, and is very easy to use (Additionally, there is a tag with the function of the fading-in of the sound effects).
For instance, to play se1.wav, write the code as follows:
[wait time=200]
*start|Start
[cm]
The sound effect is played. [l]
[playse storage=se1.wav][ws]
The end of the playback of the sound effect is waited with the [ws] tag, because the [playse] tag doesn't wait for the end of the playback of the sound effect. [playse] tag is just used to play sound effects.
The looping playback can be done with the loop=true attribute in the [playse] tag. In this case, it is not possible to wait with the [ws] tag.
Also, the [stopse] tag ends the playback of the sound effect.