I need a good midi creator something that will let me write and save a midis
and I’d like it to be a free download.
Try Anvil Studio 
I may as well ask this here…
I make chiptunes using MilkyTracker.
Chiptunes come in .xm and .mod flavors, not midi, not mp3, and their file size is usually in the bytes.
This would save a lot of load time with GameMaker, as well as the fact that chiptunes sound better than midis, but how do you get GameMaker to read such files?
We recently had a fella migrate to SCU from OCR. He’s a chiptune type guy. I’m 99% sure he’s your best bet
Get in IRC!
Like Tim, I would also recomend Anvil Studios. Easy to use, and has plenty of options.