[otrs] Authenticate agents against LDAP

Hello everyone. I have read that we can authenticate agents against LDAP I found some code in : " http://doc.otrs.org/2.2/en/html/x1643.html#configuration-agent-auth-backend-... " My questions are: 1- This code should be inserted where??? (I thing that should be on Config.pm but where) 2- When is said to take care about the Net::LDAP how can I confirm if it's installed or not? Thank you everyone.