The OWDC site requires that your browser must have be able to run java scripts. As you can see this page, it looks like this is not the case.

At some time in the near future I plan to have an script-free option but not yet. Sorry

So options for you are:
- If you are using Internet Explorer, there may be a yellow bar along the top of the page. Click that and allow scripts. Or
- If you have disabled javascripts on your browser, turn them on. Or
- Use a script capable browser. Mozilla Firefox or Internet Explorer works fine.