At present, only registered users can create and edit articles. The registration process is very straightforward. Just click the 'Register' link at the top right of any page.
After you've registered, you'll be able to login with your password at any time and edit any existing articles - or create new ones.
When filling in the form, make sure you supply a valid e-mail address - an auto-generated login password will be sent to that address.
Once you're logged in with the password you've been sent, you can of course change it to a preferred one of your choice using the 'Update Profile' link at the top of the page.