newbie needs help with simple batch file

Either look into Automator or Dropbox.

Also have a look at the following to learn more about Mac OS X:

Helpful Information for Any Mac User by GGJstudios​

 

You can do stuff like this with UNIX-style shell scripting, but that's hard to learn. AppleScript is much easier to get the hang of, and works well for tasks like this. Automator makes it even easier (just drag and drop actions into the appropriate places), but you lose flexibility as a sacrifice.

 

Unix isn't too hard if you don't mind command lines, it's the most likely of your three options (AS, Automator, Shell) to bud into something genuinely useful, but Automator is probably your most straightforward user interface friendly option.