Once you have the correct path to your plugins directory, go to the plugins admin page (Config>Plugins) and enable one of the editors (FCKEditor is available by default).
If you cannot see the , then download it and enable it instead of the FCKEditor.
There is also an editor for the CKEditor plugin, thanks to DanWaterloo for this link.
http://ckeditor.com/builder
.
There is also a available.