Once you finish signing up to Social Store you will be sent to your social store control panel where you are asked to link it with an existing Facebook page.
If you didn’t arrive at your control panel after signing up, you can login to your control panel at any time and then click on the “Add to Facebook Page” button to add it to your page.
Next, you will get this window asking you to choose a page to add your social store to.
Keep in mind that you will need to have a business Facebook page and not just a personal profile to use social store, since social store can’t be added to a personal profile.
If you need any other help setting up social store feel free to add a comment to this thread.