You can buy the hardcopy manual - see this thread:
http://www.subsim.com/radioroom/showthread.php?t=121864
This is the manual that explains how to do things, but does not provide strategy or tactics to use. The platforms are complex enough that it is a useful book to have.
The best place to get the tactical info from is the subguru.com site mentioned earlier. There are a number of white papers and a very good sub training mission/briefing for you to try.
Tom