How to access Web server behind SRX

Hello folks,

I have hosted one web server front ended with SRX firewall and SRX firewall untrust interface has public IP address reachable through internet. Now, how to access from internet the web server from internet?

I understand, we need to enable NAT, but how exactly the IP address on SRX be mapped to Webserver?

Do I need to do anything else? 

Please suggest, CLI information would indeed be helpful.

Thanks,

Shirish.