How to use MIDI song files

[Tommarr]

I am not new to MIDI, but I am new to MIDI song files.
Can anyone direct me to any basic, useful tutorials?
I'm late to the party on this one, but never had need, interest, time.
But, time for some new learning!
What are they used for?
How do I load/organize them?
Best sources?
Thanks!!

[EileenL]

Some people use them to play along to.
  I prefer to record my own midi files and then record to WAV to share with friends.

[mikf]

Basically how you use them is up to you. They are just data files that contain all the data to create the song when played on a suitable device like your keyboard.
They have some advantages over audio files - they are small size so don't use much memory, they are easily edited and manipulated on your keyboard. 
Some people use them to play on their keyboard, some play along with them, but probably the most common use is to make a recording on midi first, then do all the editing/correction before turning into an audio file.
Big disadvantage is that they cannot be used for vocals, or external instruments. But you can play them, while you layer a vocal onto audio, and a lot of people do this. 
Mike

[Toril S]

I use them to learn a song. And I make MIDI files of all my recordings.

[pjd]

Genos Owner's Manual, Chapter 4, Singing with Song Playback. [Basic features]
Genos Reference Manual, Chapter 4, Song Playback [More advanced features]

"Singing" is not quite right. More like "playing during song playback." Once you know how to load and play songs (either MIDI or audio), it's time to move on to recording, if that's your fancy.

All the best -- pj