Install EPEL and the Puppet repo first, then install puppet-server
rpm -i http://<your mirror>/epel-release-6-8.noarch.rpm rpm -i http://yum.puppetlabs.com/puppetlabs-release-el-6.noarch.rpm yum install puppet-server
Open TCP port 8140 for puppet traffic. For example, insert a rule at line 7 and save.
iptables -I INPUT 7 -m state --state NEW -m tcp -p tcp --dport 8140 -j ACCEPT -m comment --comment Puppet service iptables save
chkconfig puppet on chkconfig puppetmaster on