Right now, there is no facility yet that will enable you to edit your ad and change the city wherein you originally posted it.
We suggest that you re-post it to the correct city.
To change the city, click on city name that you will see on the top left of the home page, and then use the drop down menus to select the city.
If you chose to do this, we just ask that you delete the old ad to prevent duplicates. Duplicate ad listing can lead to account suspension.
We are continuously doing our best to greatly improve the efficiency of the site's features, it may just take us a little bit of time.