most of the information is available on the BMC docs site, it just does not list the information in a logical order e.g. sequential, and it can be confusing at first to find what you are looking for due to the amount of information available - but it is there. Maybe initally download the information as a PDF (will be quite large) that you can reference and search.
BMC also offer a huge number of education course you can take to enhance your knowledge - the system can seem like a huge mountain to tackle at first, and due to its every expanding functions and complexity, it is recommended to take at least a couple of courses to get started.
There is huge amount of information also available on this site, most questions you can think of have been asked and answered before so you can perform a search to see if it is available - e.g.:
There are documents, discussions, recorded Webinars, etc available on this site for each Product in the range (under the Content sub sections) - there are also YouTube videos also now available and frequently new content is being released. There has also been an effort to "Consolidate" a large amount of this information into reference documents that you have asked for - e.g.:
PS: Additional information on how to use this site is available here:
Great resources. Thanks Carl!
Carl covered much of what is available. Unfortunately getting your head around the Remedy basics has traditionally been a lot of learn on your own with trial and error. In recent years BMC has been trying to improve on this with the YouTube videos, involvement in the BMC Communities, etc. It is an uphill battle. AR System is a pretty in-depth platform that is unlike "traditional" programming/development platforms. On top of ARS we ave complex applications (e.g. ITSM) written support the complexities of an IT organization along with the business. It is a commitment to figure it out.
Taking some classes will certainly help kick-start the process but on the other hand many people do not get any training for many years if ever in some cases. In our case we tend to train developers in-house and send them to training once they have a basic understanding of the system. This alleviates the drinking from a fire hose feeling in class, allows them to really understand the material and even ask a bit more advanced theory/best practices questions.
If a person is committed then they need to dig in and just start trying things out using all of the resources mentioned and ask questions as roadblocks appear. One more resource not already mentioned is the ARSlist (http://www.arslist.org/http://www.arslist.org). This was the original Remedy community (20 years worth) where along with the BMC Communities you can get by With a Little Help from the List.