To connect, simply visit your shop's Info & Appearance page and click Connect with Facebook and Connect with Twitter. If you administer multiple Pages on Facebook, you'll be given the option to choose one. Linking your shop only takes a minute, and then you get a nice new Like and Follow button on your shop home - inviting all your visitors to connect with you on Facebook and Twitter.
Connecting your shop to Facebook and Twitter allows your visitors to establish a connection with you off of Etsy, too. When a shopper Likes your shop on Etsy, they will become a fan of your Page on Facebook. That means that when that shopper goes to Facebook, they can see updates you publish to your shop's Page in their News Feed. This is different from the previous experience of Liking a shop on Etsy, which did not establish the ongoing Facebook connection. If you already have fans of your Facebook Page, you'll see that number reflected on Etsy when you link your accounts!
With this direct connection between your Etsy shop and your Facebook Page and Twitter account, it's now easier than ever to promote the new items you list in your shop to your Facebook and Twitter contacts. This is exciting, and requires some learning, as simply tweeting and posting all your new items to Facebook and Twitter could get overwhelming for your fans and followers.