We have a new site www.g-lish.org where you can read all articles from This is Ghana in a much more organised fashion. Read Currency and money in Ghana there.
I found a couple of useful links that might help familiarise you with the Ghana Cedi before arriving.
The first one is from the an official government site regarding the redenomination of the Cedi in 2007. It shows the new notes and how to translate it from the old currency, still quoted on the street. Go HERE for that link.
Here is a currency converter that includes the Cedi!!!
Clap for Oanda!