Add new addons in nagios

can someone help me how to add new addons in nagios, like nrpe etc.
i have install nagios in my computer. my new task is to add nrpe and create virtual ip on same system so this new virtual ip will act as remote system. i think nrpe is used for monitoring remote system..
please help me in this

Please check Nagios documentation.
After that if you are facing any issue, please reply back.

Nagios - Documentation

Thanks