What's the adequate Java program I need to download to draw here?

I think it's java 1.4.2? Somewhere around there should be the version you need, or at least what works for me, but just update your java to be the newest version and you should be fine. Certain web browsers don't seem to load these drawing applets no matter how up to date your java is, like the version of firefox for mac, so you may need to try a different browser if your java is updated and you're still not able to draw.

There's only one: www.java.com