Go to the forums page and select either the "CP Academic Job Board" or the "CP Practice Job Board" to post a the announcement. Click on "add topic" (you'll need to be logged in to do this) then enter a title for the job post in the title field and information about the position in the summary field. Scroll down and label your post as a "job posting" and then click on "add topic".
Remember, its important to add links to more information if relevant. To create a hyperlink to your website or other information, highlight the word that you want to make a link, then click on the little chain link in the tool bar to enter the link.