Put the following in a file called description.ext, and place it in your mission directory (the same folder as mission.sqm).
class CfgMusic
{
   tracks[] = {DayByDay_Serafin};
   class DayByDay
   {
      name = "Day by Day - Serafin";
      sound[] = {\music\DayByDay_Serafin.ogg, db + 5, 1.0};
   };
};
Change the class, name and path to suit your needs.
Then, load your mission, and look for the name in the Music tab of a trigger. If you can't see it, or it doesn't play ingame, it is a problem with the bit-rate/frequeency of the file.
Sorry if that covered what you already have done, but when it comes to OFP sometimes sarting from scratch is the best course of action as it is very easy to over look the odd ; or " here and there.