(1) how to tell when to report a bug, and
(2) how to write a useful bug report and what information it needs to have.
-You can read the read the Bugs section of the manual from inside Emacs.
+You can read the Bugs section of the manual from inside Emacs.
Start Emacs, do C-h i to enter Info, then m Emacs RET to get to the
Emacs manual, then m Bugs RET to get to the section on bugs.
Or you can use the standalone Info program in a like manner.