Log into your 'My QC'
Click 'My Classifieds' on the left side of the page.
Find the ad that you would like to change and click on it.
You can then edit your ad and click 'Update Ad' at the bottom of the page to post the changes.
You can temporarily turn your ad off, then back on again.
At the bottom of the Update An Ad Page in the Site Display area there is a 'Live' and 'Inactive' choice.
If 'Inactive' is chosen, the ad will NOT display on the site. If 'Live' is chosen, the ad will display the site.
You can turn the display of the ad on or off anytime.