Welcome to the forum. That's a big ask yogi. There are so many commands that someone would have to write a manual (and they're being regularly added to by our brilliant Trainz community). There are also some that do, more or less, the same but different users prefer different commands. A number of the commands are added to the driver session by default and it may be best if you played with them first to get a feel for them.
You may be better off asking what a specific command does, if you can't work it out yourself, or if you want your AI train to do something specific then ask which is the best command to use. I'm sure that you'll get plenty of help.
