If you like books, you can probably find these at your local library:
Learning Linux in 10 Minutes
Learning Linux in 24 Hours
Learning Linux in a Year (okay, that one's made up)
My all-time favorite is "Running Linux" from O'Reilly. That will tell you everything you need to know about system administration, as well as how to use software that does well on Linux (e.g., Emacs, Perl, TeX, gcc). It's a good introduction overall, and makes a good reference.