When you click on the Help menu with any of the mouse buttons you will get the following menu items:
List symbols matching regexp:
If you type "mode" and hit <RET>, you will get a list of all the symbols (like functions and commands). You can now get documentation on any of the given symbols by "clicking" on any of the symbols (i.e. drag your mouse on the appropriate symbol and release the button). For example, if you "click" on the 'auto-fill-mode' you will get the following message in the window at the bottom:
auto-fill-mode
Function, Command:
Toggle auto-fill mode.
With arg, turn auto-fill mode on if and only if arg is positive.
In auto-fill mode, inserting a space at a column beyond `fill-column'
automatically breaks the line at a previous space.
Variable:
value = nil
variable not documented
Apropos (regexp):
Now you can give any string name, for example "mode" and hit
<RET>. You will get a listing of all the variables and commands
containing that string i.e "mode" with a short description of its
function.
C-c C-c n texinfo-insert-@node
C-c C-c o texinfo-insert-@noindent
C-c C-c s texinfo-insert-@samp
C-c C-c t texinfo-insert-@table
C-c C-c v texinfo-insert-@var
C-c C-c x texinfo-insert-@example
C-c C-c { texinfo-insert-braces
These keybindings apply only to "Texinfo" mode. See Modes, for more
information on various modes.
Describe Key:
After you type a command key sequence, full documentation of that command will be displayed. For example if you type C-g, you will see the following documentation for C-g:
keyboard-quit:
Signal a `quit' condition.
This means that C-g will quit whatever command you gave earlier.
Describe function (default <some function name>):
If you hit <RET> without giving a function name, you will get documentation for that default function name, otherwise if you type a function name and hit <RET>, you will get documentation for the given function.
Manual entry: (default <some name>)
Now you can type any command, for example type ‘who’ and press
<RET>. You will get the man page for the Unix command ‘who’ which
lists who is on the system.
For more information on the Help facility, See Help.