I found a flashcards program in that case (I assumed being in Hong Kong you wanted Cantonese

), but you must have the ability to have Chinese characters installed on your BlackBerry:
Mobile Chinese Flashcards - Learn Chinese on your Mobile Phone
If you don't have a firmware with Chinese, you'll have to upgrade your 8800 (or downgrade? depends on version) to get one with Chinese. I was going to try and help you find a firmware for the 8800, but the RIM blackberry.com download servers are crashing right now. :(