You can allow your users to sign up and log into your site with their data at Facebook.
1. Go to developers.facebook.com/apps
2. Navigate to My Apps.
3. Click on Create App
4. Put some name and your email, then click on Create App ID
5. Click on Add a product
6. Find Facebook login
7. Click on Set up
8. Find on the left side in Products Facebook login and click on it.
9. There you should see something like that:
10. Go to Settings of the Facebook Login.
11. Find the line Valid OAuth Redirect URIs.
12. You should put there OAuth URI and Admin OAuth URI that you can find in your administrator panel>System>Social networks>Facebook>Application
13. Go to the basic settings of your Facebook application. There you would need 2 parameters: App ID and App Secret. To show App Secret you would need to click the button Show and put your password. Then copy them to the above-mentioned page in your admin panel.
14. Put your domain names in App Domains and save.
After you’re done, switch the app from development mode to live mode.
15. After that, go to the page in your administrator panel>System>Social networks and click on the button No on the facebook line.
This is what you will see in the user interface:
To add the developer to your Facebook account, to need to follow these steps:
1) Go to https://developers.facebook.com/apps
2) Go to "My Apps", and select your application or create an application if it has not been created yet:
3) Go to "Roles":
4) Click "Add Developers":
5) In the window that opens, enter the username of the developer account.
6) After that, the developer will be able to accept the request.