Seeking Mikrotik Experts

Hello pros, i would like to request some assistance in for NAT-ing for my CCR2004.

I have 2 ISP,
1 unit of CCR2004-16G-2S+
1 unit of PALOALTO FW
3 Public IP

I would like to assign 1 Public IP to my FW (for me to access from outside). Below are my network topology:

Incase the photo unable to be seen:
https://ibb.co/grRGxKk

May i know the configuration that i must do? I have very basic network knowledge and currently able to configure the router using winbox.