The first thing to do is to make sure you're registered. This registration - which is free - is not the same as the one you use on RR. You need that registration to access the editor. Download the page for a quick guide to the Wiki editor.
There's probably a way to create an indiependent page (one that stands alone, and is not linked from anything, but I don't quite know how to do that yet. So, see if the idea for your page can be branched off a page that already exists, or needs a completly new category. If it needs a new category, Lindsay needs to put a page link onto the Wiki main page for it. However, if it can be linked via another page, simply edit the page and put the title in double brackets like this [[new title]]
When the new title is resolved on the page, it will show up in red. This is wiki-ese for 'I can't find this page'. Simply click on that, and you will be taken to the editor.
I'd suggest coding your page off line first (in Notepad, or whatever editor you fancy). That way you can refine it a little before putting it live. Then all you need do is copy/paste into the editor, and you're on your way.
One tip that I've found - the Wiki language is sensitive to soft spacing (what happens when a line that is a little long wraps). Be careful of this, and you should be fine.
73s and GL...Mike