You are stuck in bootloader mode. Use the following link. You might try the UNI app mentioned part-way down the first page first. I hear that it is easier. You can also jump in the chat room if you need help.
http://www.ppcgeeks.com/for-those-of...ootloader.html
Once out of bootloader mode, you might want to make sure you flashed your latest Official upgrade to make sure everything is cool before going back to a custom rom.