Install Zabbix agent daemon into your system
apt-get install zabbix-agent
then change in file /etc/zabbix/zabbix_agentd.conf three parameters:
Server=IP of Zabbix Server
ServerActive=IP of Zabbix Server
Hostname=use the FQDN of the node where the agent runs
Do not forget to allow zabbix in your firewall rules. Zabbix agent listens on port 10050 TCP.
Then simple restart agent
service zabbix-agent restart
Thats all.