On any Unix-like system, there is command-line documentation. You can read about the syntax and function of basic commands (say ls) by typing man ls at a shell prompt. More extensive documentation is often available by typing (e.g.) info ls instead. Finally, if you want to know what commands are related to a word (such as ``list''), type apropos list. The output of apropos contains short descriptions; you can then read the man pages for likely-sounding choices.
GNU/Linux is not produced by a centralized entity, and does not have a centralized and administered support system. However, there are abundant resources on the Internet (USENET newsgroups, web sites, local users' groups, and mailing lists), and helpful answers to specific, intelligently-worded questions are usually received within hours of the question's posting to a newsgroup. GNU/Linux users and developers are a community, and no one is scorned merely for being a beginner.22 Part of the challenge is in learning where to look for help when a problem arises. There is extensive written documentation, both in the installation on your machine ( aside from the utilities listed above), and on the world-wide web. An excellent search engine is Google http://www.google.com, from which you can quickly find sites geared toward almost anything GNU/Linux-related (or, really, anything). Google, incidentally, runs on a GNU/Linux supercluster, a networked array of machines all running GNU/Linux. It is incredibly fast, and stunningly accurate for most searches. A search for Linux Howto will return several sites at which up-to-date versions of the Linux How-to documents can be obtained.23
There are print and online journals devoted to GNU/Linux. Distributors have web sites with bug fixes, security updates, tutorials, and copious links to other related sites. You will have far more trouble trying to decide where to get help than you will have finding help. The ideal solution is to find a local LUG (Linux Users' Group) and attend meetings, converse with other members by email, share tips and solve problems, and help other newcomers find their way. Barring that, there are numerous web-based chat groups, where people post questions and answers, and share information at all levels. There are several good books on several aspects of GNU/Linux system administration, many of which can be downloaded for no cost and viewed in HTML or printed in PostScript.
Eventually you may want to download and install software; this is typically not difficult, but there are a few standard precautions. First, you should never download software as root. In fact, you should never do anything over a network as root; it's the equivalent of shouting your credit card number in public. Second, you should only download software from large, reputable sites. A potential danger in downloading software is the possibility of unpacking and running a trojan horse, which is a (usually malicious) program that has the same name as a system utility but which does something else (or in addition). An example would be a program that calls itself ls (same as the ``list'' command) that does indeed list directory contents, but also starts a daemon that captures keyboard input and mails it to a remote machine. The next time you log in, your password is compromised. This type of exploit has happened in the past and is an ongoing possibility. (Think of telephone scams where someone pretending to be from a credit agency demands your card number.) Third, it is a good idea to unpack the downloaded software as an ordinary user. That way, if you have downloaded a malicious program disguised as something innocent, you only risk trashing an ordinary account and not the root account. Finally, depending on your level of caution, you may want to use encryption for downloading (and for network activity in general), and use ``checksum signatures'' (try apropos check or man md5sum) to verify that the file you downloaded really is the advertised, untampered package.