To use Emacs, do
C-h i (this takes you into Info),
m (which offers the menu selections) followed by
latex (at this stage you can already use the completion
mechanism of Emacs), and finally RETURN.
Details about the use of Info are given in the Emacs section, under Info.
You can find here the HTML version of the Info LaTeX pages (version 1.6, from April 1996).