The easiest way is to write a shell script that uses the 'useradd' and 'mail' commands. Use the 'crypt' command to turn the password into encrypted form for useradd.
Shell script tutorial:
www.linuxcommand.org
Shell scripting is *very* easy and very useful, so it's worth going through the tutorial and learning yourself, rather than just copying somebody else's. If you can't make it work then post your script to a forum and somebody can give you exact help.