If you would like the recipe for it, here is a neat pictorial explanation: How to Make Onigiri [in English] and Onigiri [in Japanese]. ~!!!
And Joshua, we already have a thread devoted to Japanese Food, so please do post anything else regarding Japanese cuisine in that thread. Thanks. ^_^ Here is the link for that thread: Japanese Food Anyone!
Lastly, enjoy the recipe. It's pretty simple, so you should be able to follow it easily.