Look in the MFME v20 install folder and there's a file called Tips, which contains lots of helpful info and shortcuts.
One thing that MFME never had, was a really good general users guide. I started to create one back in the day, when I used to create disks for mates. Just about how to load games, do some simple edit, view meters etc...etc...
Regs guide for dummies about layout creation was great though and is easy enough to follow, to get anyone interested in layout designing started.