Wiki Guide
This wiki uses MediaWiki, the same software used by Wikipedia. It is set to be publicly viewable, but only users can create or edit pages. Creation of new users is restricted to administrators. Contact Matt Kelley if you require editing privileges.
The main page can be accessed from anywhere by clicking the Aldersgate logo in the top left or clicking "Main page" in the left sidebar if viewing this on a desktop computer. If viewing from mobile, click the ≡ icon in the top left, then click Home from the menu.
It contains a site map that should cover all major topics of interest. You can also use the search at the top right to find what you're looking for.
Editing
The help link on the left sidebar (assuming you are viewing this on a desktop computer, which should likely be the case if you are trying to edit) provides a ton of useful information about editing which need not be reproduced here. I will note that Visual editing is enabled, which makes casual page authorship much easier as you can edit in an obvious fashion that looks like an average document editor. It might also not be completely obvious that creating a new page can be done by simply attempting to navigate to the non-existent page, most easily done by adding a link to it (which should be done on the Main Page first anyway). Hence, just edit the Main Page, add the link, save the Main Page, then click your link to start building the page.