As Linux is a Unix-like operating system, a general familiarity with fundamental Unix concepts such as the Unix directory hierarchy and file permissions is essential. Fortunately, there are many Unix tutorials online that collectively cover everything a user might need to know to use Linux. I suggest you bookmark the following as an online reference library :
The Digital Unix Manual is a great reference as seen in this Table of Contents
UNIXhelp is mirrored on many servers around the world. It is a useful resource for newbies.
Unix is a Four Letter Word... is another resource suitable for newbies.