Add the Pinterest "Pin It" button to your ecommerce site, right next to your Facebook Like button. This makes it easy for your website visitors to add images from your product pages directly to their boards.
Engage with the community. Like all other social networks, you need to listen and engage, not simply broadcast your message. Try allowing members of the community to post to your boards, but be sure to monitor activity for appropriate content. When users upload their own pins to your boards, your themed boards will grow and you'll quickly become part of the community fabric.