If you just created your Facebook app, you first need to add the Facebook Login product. You can do this by clicking on the + Add Product link in the PRODUCTS section on the left side of the page and selecting Facebook Login on the resulting page.
After adding this product, you can find the settings on the next page
https://developers.facebook.com/sa/apps/YOUR_APP_ID/fb-login/
Please replace YOUR_APP_ID with your real application identifier, which is a string like 078717227531318 .
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