You must load Para mode before using it. In particular, you must have alreaded loaded `para.el' before loading a file with a Para mode specification; otherwise, Emacs signals an error saying `void function: para-mode'.
You may load `para.el' manually or automatically. To load it manually, find the file and then evaluate the buffer with the `M-x `eval-current-buffer' command; or else type `M-x load-file' and then type the pathname for `para.el' when prompted.
To load `para.el' automatically, you could put either of the following in your `.emacs' file:
(autoload 'para-mode "para" "Hypertext-like extension of Texinfo. Provides editing and Info-like movement commands for Texinfo files." t nil)
Be sure that `para.el' or `para.elc' is in your load path.
NOTE: The standard Emacs 18 distribution loads version 1 Texinfo files. You need to place version 2 Texinfo files in the load path in such a manner that the load commands will load the version 2 Texinfo files and override the version 1 Texinfo files.
In your `.emacs' file, you might set your load path in a manner similar to the following example:
(setq load-path '(nil "/u/texinfo2" "/u/para" "/usr/local/lib/emacs/lisp")
(If the first element of path is nil, it signifies the current directory.)
(You may want to byte-compile `para.el'.)
The autoload function is usually preferred to the straight use of load, since autoload will load a file only when you need it.
If you either load or autoload Para mode, a file with `-*-para-*-' on the first line of the file will start out in Para mode.
You may also place the following autoload command in your `.emacs' file:
(autoload 'para-make-file "para" "Create a Para Mode file and insert its header." t nil)
This command will load Para if you are creating a Para Mode file.
Finally, you might want to add the following autoload command:
(autoload 'para-add-node "para" "Add a node to a Para mode file." t nil)