App ID

Hello My name is Andrea Lolli, I have two Facebook pages
-1 ° https://www.facebook.com/pennabianca24 official Facebook page (my staff)
-2 ° https://www.facebook.com/MercatinoPlus Secondary Facebook Page (website)
On my site with WordPress MercatinoPlus fact I installed a PluginFacebook

For https://www.facebook.com/MercatinoPlus I need to know the (App ID — App Secret)
In summary I need to know where I find the (App ID – App Secret – Facebook / mercatinoplus)
You can do THANKS