Any suggestions on teaching babies sign language?

I have a 2 1/2 year old with a speech delay,her therapist wants me to teach her sign language. I also have a 12 month old, and I figure if I’m going to teach one, I should teach both. Any suggestions, books, video’s you could recommend. Thanks!!!
Thanks lucky, I knew sign language years ago, so I am trying to refresh my memory right now.
.