copy the sample.nanorc from the doc/ directory in the nano source package (or from /usr/doc/nano on your system) to .nanorc in your home directory, and then edit it. If you didn't get a sample nanorc, the syntax of the file is simple: features are turned on and off by using the words set and unset followed by the long option name of the feature (see man nanorc for the full list of options). For example, "set quickblank" or "set smarthome". Of course, for this to work, your nano must not have been compiled with --disable-nanorc.