Hello,
The following threads might help to assist you with these concepts. The first is a discussion on the Good itself:
http://network54.com/Hide/Forum/message?forumid=46726&messageid=968905590
The second is entitled "The Allegory of the Cave and the Divided Line" this deals with Plato's Forms and might help you with the insight that concepts like the Good, justice, etc. are concepts with various different meanings, these concepts also are thought to have a universal Form, as Plato describes in the Republic.
For more on the Good and on Plato's theories you may want to refer to Plato's "The Republic" and "Crito" which can be found at various sites around the net.
Good luck.
-Platonia