From Beachapedia

Beachapedia runs on a slightly modified version of the most recent version of Mediawiki server software, the same software that runs Wikipedia. In order to create and format your pages correctly, you'll need to have a basic understanding of the special codes used by Mediawiki. This may sound intimidating, but is very simple once you get the hang of it, and is no harder than learning upgraded versions of popular software, like MS Word.

Luckily, the users at Wikipedia have created a very nice tutorial that walks you through the basics step-by-step.

If you are not already familiar with Mediawiki formatting, I would highly recommend working through this short tutorial.