You need to do a search on the net. There are other threads on here and other places that can get you started. Google Search is your friend.
You will likely need a factory manual for your car depending on what the year and make are to find out what the ID's are for what modules. In my GM manual for my 2003 Avalanche they are listed by module, what they support and what their ID's were. Beyond that you won't find much information beyond the generic information about what you do to control each module. More specifics will depend on your vehicle and if you can do a search and see if anyone has posted information.
To get the information from the manufacturers depends on the manufacturer but generally they will only release the information to a business, you need to sign a non disclosure agreement and it generally is costly.