The url is
you attach the course when you open the wwlink block in the course itself. You need to do this before you can create any webwork assignments. (Choose turn edit on, then add block on any course home page.) Each moodle course can be matched with a different webwork course.
I tried to attach to your webwork last night from the moodle here and everything seemed to work except that I didn't have your security code.
If you haven't attached a course with the wwlink block then you will get (unhelpful) error messages when you try to create an assignment. The moodle end of the setup still needs work in terms of error reporting.