Mary, I think abc notation is about the quickest way to get tunes in. Then use one of the abc to MIDI programs (preferably mine!). My HARMONY program, mainly intended to add chords, also puts GM reset codes into every MIDI file it creates, and will be able to add system exclusive code in the future. (If you don't know what these are, it doesn't matter).
My other utilities (not yet all on my site) can do miscellaneous jobs like
changing the master volume for each channel (to fix badly balanced files)
inserting mid-tune key changes
muting unwanted channels/tracks (but not deleting, so you can unmute)
changing the tempo
Turning a MIDI into a KARAOKE file