If you dont have Photoshop download GIMP http://www.gimp.org/downloads/ It is free opensource image manipulation software... damn near as powerful as photoshop, handles about the same, has a Mac look to the interface. I teach adult ed classes on it at the community college and people love it. lots of online tutorials to get you started though. Did I mention that it is free.
Lol I did, I swear! I have the .psd file on my computer. Only course I took on photoshop was back in grade 9 or 10, I just enjoyed using it so I leared how to do stuff. I only know how to use the basic interface, not sure how to do stuff with filters and wahtnot although I'd like to learn.