~/ takes you to the home directory, .gnome2/ is the directory in the home directory.
Configuaration files are usually in hidden folders in your home directory, so you could also perform a search:
takes you to your home directory
$ find . -name ".gnome2"
this will look for the directory recursively starting at "." which is your current working directory (where you are at now) for the -name (self explanatory) ".gnome2".
Look at "find" and "locate" howto's some time. Those are pretty useful. I see there is no "plugins" directory in my gedit folder, you might have to create it.