Ok on this its pretty easy, it is just a matter of finding a song, saving it, and changing the name.
1. What you have to do is find a song in Midi which is no words or actual instruments its basically made on the computer (ex. linkinpark.midi) so go to google and search midi, when you find the song that you want save target as or save link as and it will be saved where ever you put it
2. Move the song to your mfx folder (C://Program Files/EndlessOnline/mfx) and change the name to replace the song that you want to change (ex. mfx001 [Title Screen song]) Note: You must change the name to the same thing as the one your replacing or else Endless wont work
3. once you have made all of this and finished it close out the box and Open eo, your song should be playing where ever you set it to
Note: Mfx is the easiest patch to make and requires no skills except for typing and finding, if I didnt explain anything or you didnt quite get it reply to this topic and I'll try to explain it a little better