When i click on "Post an Ad" on your site i get this error message:
This ad has already been published or you do not have permission to activate this ad. Please contact the site admin if you are experiencing any issues.
Something is messed up on your site, maybe thru modifications from you (editing files)
I suggest to overwrite all the files at once to get rid of the problems. I suggest this "hard" method, because your site is still new and no ads are up.
Who installed wordpress and classipress for you on the webspace? Do you have an technical admin?