Hiya! And welcome to our Wiki!
WikiWiki is Hawaiian and means "quick". The original idea of WikiWiki was to create a collaborative, fast environment which would still be persistent.
Anyone can contribute; yes, you can delete what other people said, and even delete whole pages, but surprisingly, wiki does work.
When editing, you can easily create (and you should create) hyperlinks by just putting the word in square brackets, [like this]. If the page you are referring to does not exist, the resulting page will show the name in red, underlined, with a following plus sign. Like this: This Page Does Not Exist. (Please don't foil this example by creating that page...)
Wiki is and should be simple. This is why there is no need for complex HTML. You can get some effects, such as bold text and italics, but nothing very complex. Layout is the problem of the Wiki itself. There is more information in the full notation guide.