Everything up until the final challenge is coded through a java applet. Pick your preferred language (for the proper syntax highlighting and compiling), type your code into the window and submit.
You pick a challenge, 250pt, 500pt, or 1000pt. Once you view the challenge, the timer would start. The quicker you get it in, the more points you can get. The challenge will tell you what class and method names to use and provide sample results for testing.
"Using Unix is the computing equivalent of listening only to music by David Cassidy" - Rob Pike