Please help me to install Varnish on centos 6.5 apache server

sir i am trying to go through this command /usr/sbin/visudo its ok 1st time but after saving it esc ctrl zz button to save its chowing [+1] stopped /usr/sbin/visudo why its stooped after saving it please help

Hi, I am facing following issue, when i was trying to update this particular plugin on my centos droplet... The update process is starting. This process may take a while on some hosts, so please be patient. Updating P...