As WordPress features an editor allowing you to live edit your theme, it also provides another editor for editing plugins. Chapter 4 covers plugins in detail.
To access the Plugin Editor, log in to your WordPress Dashboard and go to Plugins | Editor located at the top of the screen. Then, select the plugin to edit from the list located on the right of the screen.
The built-in Plugin Editor works in exactly the same way as the theme editor. When a file is modified and saved, the modifications are written directly in the source file—there's no copy or backup.
Similar to the Theme Editor, even the Plugin Editor is a very useful tool. However, it also can raise problems in the case of a mistake in the code.
Unless you're very sure about what you're doing, always deactivate the plugin before editing it.
Always have a backup of the plugin you're editing, as the Plugin Editor does not save any revisions.
If—after editing a plugin—your blog is messed up, deactivate the plugin, and upload your plugin files backup to your
wp-content/plugins/yourplugindirectory.