Your listing may not show for a couple of reasons. It may be that the database has not updated yet. Currently the database updates only once a day at midnight, Pacific Standard Time.
Another reason might be that you have not selected to "post" your listing. Because some users don't complete their listing right off, or may wish to take it down later, posting a listing is a separate step. So make sure your listing says "this listing is shown."
Finally, you may have entered your zip code incorrectly or used a zip for a country that is not supported yet. (We're still US only.) Our program will not always pick up these errors, and may appear to confirm that a listing is posted. So make sure your zip is a five digit US zip code.