procmail

As a college student, taking computer science, I have many unix accounts.
I am aware that procmail will allow me to keep mail at one address and
also send a copy to another adress. I am, however, unaware of how to make
procmail work for me. ie: I want to receive mail at wam.umd.edu, and I
want the mail to stay there, but I would also like a copy of mail that 
is sent to wam sent to another address. How can I do this.  Thank you.