In order to edit the META tags in SiteBuilder you should first upgrade to SiteBuilder Pro. You can purchace the upgrade from the Order tab in your Customer's area.

Then you should follow these steps for editing the META tags:

1. Log in to SiteBuilder and choose your site;

2. Click on the Search Optimization Tab and make the necessary changes

3. Save and republish your website.

You should bear in mind that you can edit the META tags only with Sitebuilder Pro.