Under the Facebook Shop tab, click "Install"
Click on "Connect with Facebook" (if you are not currently logged into Facebook, it will ask you to do so at this point)
Click on the Facebook Page you would like to link your store to
Click on the "Add Tab Now" button
Click "Add Shop Builder"
Facebook does not allow us to insert your shop into your personal profile, so you'll need a Facebook Business (or Community) page. If you do not have one yet, just sign up for one here.
Once you have inserted your shop into your Facebook page, you can set it up so that users are automatically directed to your Shop tab. Click "Edit Page" under your profile picture and then click Edit for you Wall Settings. Where it says "Default Landing Tab for Everyone Else" select "Shop".