That's a Graham question for sure, but as far as I know anyone can create an article.
Articles do require approval to post once completed and Graham usually does a bit of fiddling to make everything look good. "Approval" is little more than a once-over to make sure the article is not spam nor totally bogus. I don't believe we've ever rejected a posted article.
Chances are there is an issue with session syncing between the forum/article site software. The easiest way to tell is to visit any article and check in the right sidebar (the same sidebar with the forum/article feed) for the "Member Access" module. It should have your name and a logout button if you are logged in. Could you let me know either way, cheers!
From there, simply click "Create / Edit Article" in the top menu (in "Site Tools"). Jon linked one handy reference, here is another Create Articles
Tip - before saving your article, select all the content and copy to clipboard.. just in case your session expires etc.