Try fullcircle magazine starting at issue 14 for a tutorial you can
download all that you want there and they are free.

A list of commands and help can be found here:
http://www.oreillynet.com/linux/cmd/

Use the man pages to find how to use various commands. To use the man pages
type man <commandname> in either a web browser or terminal. This is handy
once you know the command but still have trouble with syntax.

gnu.org has quite a bit of documentation, including a list of shell commands.
They all have documentation which you can access from the man command:
man ls
for example, to see the options for the ls command.

To exit from man, press "q" for quit. I found it very frustrating that ESC, "E"
and "X" do nothing.