I found an introductory course that gives a basic introduction to digital art and photoshop on cgcookie concept art channel on youtube.
Here is the first video in the series https://www.youtube.com/watch?v=nN9gmMOpIvA&t=0s&list=PLLvF9bS4OaDnyy3MvYb5MUp4uKyAgmwcS&index=2.
