A Question on Sitebuilder Pages
Using Jamroom
SiteBuilder pages can only be edited by admins so the answer to your question is 'no', but I can suggest a workaround.
Have your users create and manage their advert content via a blog post with a category of 'advert' (say). You could then update your SitBuilt page to list Blogs of that category. That way, the adverts would always be current, with no intervention from you.
hth