SEMSEOWizard.com  is one of our favorite bloggers for ecommerce SEO and social optimization tips. The Wizard is a big fan of 3dcart and has some awesome tutorials worth checking out.
One of which is this awesome tutorial on how to add the 3dcart shopping widget to your blog like this:

How to add a 3dCart social commerce widget to your site or blog

You can check out the rest of the tutorial here

Other 3dcart posts from SEMSEOWizard posts worth checking out:
How to build a website 101
Showing products on a #3dCart Blog