- Login and register your Facebook developer account https://developers.facebook.com/ (you must verify your phone number, then register FB developer account)
- Click my apps menu in the right hand, then select Create new project (or edit old project)
- Select Facebook login in the Add a Product menu. Click Set up
- Select web
- Enter Site url then click Save
- Copy your app id in the top
Then Active app from Off to On. If you did not enter app information. There is a popup, please click Basic settings link in the popup then fill all required fields
- Select Settings > Basic and add web user and seller domain as screenshot below
