The plugin uses the IDs values, the ids are the number used to identify the object, such as a item or skill. To know the id of an item, skill, element... anything, just go to the database, and check the number on the side of the object's name.
Anyway, if you're starting with rpg maker, I suggest that you try to use some easier plugins until you get more used with it. This plugin has one of the most complex setups (among my plugins, it is without question the hardest to setup until now) and is not begginer friendly.
Also you should watch the video, if you follow exactly what it shows, you will be able to, at last, have the plugin working, just copy exactly the same values as the examples given.