To save the designs to your own site, select the first Content Box in the breadcrumbs (above) and select the Styles & Templates drop down in the Content Box menu. Click the Save Template button, give the design a name and save it.
When ever you want to use the design you saved, just drag a Content Template element into your page or post and select the design.
Full step by step instructions are available HERE. Make sure you're logged in before clicking the link.