Currently you can edit your articles as long as you arrive at your article via the drop down menus at the top (ie not the latest frames boxes).

Once you have written an article and published it you can come back and edit it at any time providing you are logged in and you are the original author.

If a page is editable by you, you will see a little edit icon at the top of the page.

Clicking this will take you to your editable listing.