Before you click through to 'rehearsal the wiki', here is a brief guide.. the wiki page is designed to be interactive - you can contribute to the debate and the definitions.
This is how it works - click on the link; http://rehearsal.tiddlyspot.com/ ;a new page should open in a new window.
Explore some of the content, and the definitions that are already around by rolling your cursor over the highlighted words (known as 'tiddlers'). Click on a tiddler and it opens; roll over the menu and 'edit' is highlighted. You can edit or add content. When you have finished find 'save to web' on the right hand menu.