Gzip Compression on Centos 6

I have created a server on the centos 6 platform 64 bit and we are currently trying to enable the gzip compression to make our website load faster. Now we have read several different articles to make sure this works first we needed to make sure that module was installed we checked that and it does show as being installed and we also heard that by default it’s installed with the setup of the server we are running the vesta control panel. Based off our research you can set the compression by either doing it on the server or by doing it in the htaccess file so we tried adding it on the server side we tried adding the following code “AddOutputFilterByType DEFLATE text/html text/plain text/xml text/css text/javascript application/javascript” in the following file “/etc/httpd/conf/httpd.conf” and still came back with no results every time we do this we are restarting apache to see if it’s takes effect we even rebooted the entire server to make sure everything restarts. We have also tried putting that code in the"/home/admin/conf/web/httpd.conf" as well with the same no results. If somebody can give a step by step on what we may be doing wrong maybe there’s a way to check if gzip is installed with certain commands and also which file do we actually modify to make the compression work. thank you.