Putting image into program

Hey all, this is my first post and I have a quick question.

I've just started a computer programming class this year and we are using sun one microsystems with java and what not. I have a project in that class to do and so far I've made a basic ballbouncer program. The teacher wants us to use something we haven't done in that class yet and I was wondering how I could change the ball into an image of something like maybe a car or a spaceship. I figured I would have to save an image first and then transfer it to the program but I don't know how to do that exactly. Any help would be great, and I know this isn't that great of a challenge, but I'm still new to this stuff and any helpful criticism would be much appreciated. And sorry but as of right now I do not have the code with me, it's saved to my school's computer. Again any help would be awesome!
thanks!

Probably should go read the Tutorials on the Java website