For a general introduction to LaTeX, including the new features of LaTeX2e, you should read LaTeX: A Document Preparation System by Leslie Lamport [3].
A more detailed description of the new features of LaTeX, including an overview of more than 150 packages, is to be found in The LaTeX Companion by Michel Goossens, Frank Mittelbach and Alexander Samarin [1].
For more information about the many new LaTeX packages you should read the package documentation, which should be available from the same source as your copy of LaTeX.
There are a number of documentation files which accompany every copy
of LaTeX. A copy of LaTeX News will come out with each
six-monthly release of LaTeX; it will be found in the files
ltnews*.tex. The class- and package-writer's guide LaTeX2e for Class and Package Writers
describes the new LaTeX features for writers of document classes
and packages; it is in clsguide.tex. The guide LaTeX2e Font Selection
describes the LaTeX font selection scheme for class- and
package-writers; it is in fntguide.tex.
We are gradually turning the source code for LaTeX into a LaTeX
document LaTeX: the program. This document includes an index of
LaTeX commands and can be typeset from source2e.tex.
For more information about TeX and LaTeX, please contact your
local TeX Users Group, or the international TeX Users Group (see
page 
).