First of all we need an mp3 to OGG converter (as music in l2 is OGG formatted) such as Alt WAV MP3 WMA OGG Converter. When you download your converter, convert your favorite mp3 into ogg and go IG using a latest rev of l2j. Go to admin panel and click music... start testing the musics till you find the town you wish to add your song... Now we go to the music folder of lineage II in program files and search for the file's name we wish to replace with our song (you will find it IG as i said before...) and delete it (or keep it for backup :P) and we add and rename our song (in OGG format of course). That's all, now go IG and enjoy your favorite music ;)