Here you are going to simply add some POOL information to the PHP-FPM setup that you have already done. Unknowingly when you entered the command to install PHP-FPM, the system setup a default configuration for PHP-FPM. So most of the heavy lifting has been done for you.

You may have to do one thing and that is to create a directory where you want your Sockets to live while they are alive. I placed them here: /var/run/php5-fpm/ You can use this command to create the directory.

mkdir -p /var/run/php5-fpm/

This directory may already exists by simply installing PHP-FPM. This is the place where your file sockets will exist when online. Once you are sure that this directory exists there is nothing further you will need to do with this directory. Sockets will automatically spawn here provided you are using the virtualhost setup and PHP-FPM pool template provided.

To complete the setup move to the directory /etc/php5/fpm/pool.d/. It is here that you will setup the different UNIX Sockets that PHP-FPM will function on. 

Please Note:  In order for your system to function properly you will need to create a new POOL for every Virtual Host that you had setup.

The pool files should follow this naming convention: YOURDOMAIN.conf

Here is a template for the pool files.

[DOMAINNAME]

listen = /var/run/php5-fpm/DOMAINNAME.socket
listen.backlog = -1

; Unix user/group of processes
user = (THE USERNAME OF THE USER THAT OWNS THE SITE FILES)
group = www-data

; Choose how the process manager will control the number of child processes.
pm = dynamic
pm.max_children = 75
pm.start_servers = 10
pm.min_spare_servers = 5
pm.max_spare_servers = 20
pm.max_requests = 500

; Pass environment variables
env[HOSTNAME] = $HOSTNAME
env[PATH] = /usr/local/bin:/usr/bin:/bin
env[TMP] = /tmp
env[TMPDIR] = /tmp
env[TEMP] = /tmp

; host-specific php ini settings here
; php_admin_value[open_basedir] = /var/www/DOMAINNAME/htdocs:/tmp

Please remember to replace all instances of "DOMAINNAME" with then name of your domain.