Include a PrestaShop ecommerce website to your blog.
Include the header and footer of your ecommerce website on your blog.
You need to install the PrestaShop module for WordPress on your ecommerce website to use this plugin : http://prestashop.joelgaujard.info/product.php?id_product=17
Some functionalities :
You must read this tutorial : http://blog.joelgaujard.info/tutorial/tutorial-prestashop-wordpress