The real (developer) manual is inside the FrameMaker installation, e.g. on our site it is:
/unige/frame_6.0/fminit/usenglish/OnlineManuals/FMSGML_Dev_Guide.pdf
Once you found it, get a double monitor system (20' or better) and launch Acroread. Else print the 570 pages (both will also do). Just to make sure: There is NO printed manual you get which is of any use for the task of setting up an SGML Application (fancy word for the many things you have to declare and define before you can start writing). The books you get are only good if somebody at your place already did what you hopefully will learn here.