Oh I see they have a tutorial here-
http://www.nlm.nih.gov/bsd/disted/pubmedtutorial/
but I usually just do a search of what I am looking for in their search box in the top - RSD or whatever and hit go- then explore more from there.
here is RSD -
http://vsearch.nlm.nih.gov/vivisimo/...m-main-website
hope the link works for you.