The simplest way is to create a link to it in an existing article and then click that link.
For example, if I wanted to create an arcticle titled; "Argument from sexual euphoria", I could go into an existing article and add:
[[Argument from sexual euphoria]]
Click "Show Preview" and then click on the red link that reads "Argument from sexual euphoria". That will open the new entry for editing. (Show preview, instead of saving, ensures that you don't change existing content)
You can also edit the URL directly. If you're on the article for "Salvation" for example, the URL will read:
You can change this to read:
http://wiki.ironchariots.org/index.php? ... l_euphoria
And, lastly, you can enter "Argument from sexual euphoria" in the "Search" box and then click the link that says "create this page".
There's an announcement in the main announcements forum with links to editing guidelines and helpful information at wikipedia.