you mean:
If you want to smooth out your registration process for your customers, you can allow them to use their facebook account to register during the Checkout or on the HikaShop registration page. That will make it easier for them.
First, you need to setup the Joomla FaceBook Connect extension on your website:
extensions.joomla.org/extensions/social-...ook-integration/7215
Then, you can edit the file "registration" of the view "user" via the menu Display->Views of HikaShop and add the tag {JFBCLogin} right at the beginning of the file.