on my Blog, I have a detailed method I use for making music files here:
How I make lotro music files.
I also have been using Fire Ferns ABC conversion site you will need to register there, and then you can start creating files from midis. ( THey have a tutorial up ) And, finally there is Digero's Maestro which works fairly well, but not always perfect.
I prefer to edit now, with my method, then made a new midi, and upload it on Firefern's to finish.