Create a Facebook App
before creating the Facebook comments you need to have your Facebook App first if you already have you just skip this step.
Go to https://developers.facebook.com/apps/
click Add a New App
fill Display Name
and Contact Email
click Create App ID

Generate code and import Facebook SDK from the Facebook developer page
go to https://developers.facebook.com/docs/plugins/comments
add initial URL at field URL to comment on
don’t worry you can change it later
set the width to 100%
set number of posts mean number of posts will show immediately and for other user need to click show more for it
click get code 
select your app ID you need to use the API for and select language you want for the SDK 
copy these code and drop to your page
change data-herf
to your page URL