Once you have begun to post jobs you can go in and edit your listing. To do so, got to the jobs board and click the "My Jobs List" button. Click that link as shown below. 

Once in here you will see a listing of all the jobs you have posted as shown below:

To edit OR delete a job posting, click the Job Title in your list. The listing will then appear as below. Note the Delete and Edit buttons.

 If you select Delete, a confirmation window will appear. If you Edit, a form appears for you to make changes and then click the "Save" button as noted below.