Define your sound in the description.ext like any other sound
class CfgSounds
{
sounds[] =
{ yoursound };
class yoursound
{
name = "yoursound";
sound[] = {"yoursound.ogg", 1, 1.0};
titles[] = { };
};
};
then put the :
OnBriefingGear "yoursound"
in the init.sqs, thats it, you can have one for briefing, notes, gear selection and group info, it will play the first time each page is viewed.