This wiki is powered by DokuWiki. If you have used a wiki before, you should be fine. Otherwise, this page should point you in the right direction.
DokuWiki uses a wiki language to create the pages.
There's a helpful toolbar in the editor, making it much easier to write pages.
You can preview pages before saving them, which is really useful for checking that DokuWiki actually does what you expect it to do with what you've typed - especially when you're getting used to the syntax.
DokuWiki will autosave your edits as a draft every 30 seconds. If something goes wrong, you should be able to get your draft back again. Don't forget to save the page when you are finished though!
You can still write HTML for the pages if you prefer.