Original IP by Cloudflare

Hi, I'm using Cloudflare to accelerate, it works smoothly with nopcommerce22, but all access ip has been shifted to Clouldflare's IP. I found the below words from Cloudflare to explain how to get original IP.

           "Please change the string as below:

             // Old way of getting the IP Address string IPAddress = Request.UserHostAddress;

             // New way based on the http headers string IPAddress = Request.Headers["CF-Connecting-IP"];


              (If you're using ASP classic: Request.ServerVariables("CF-Connecting-IP") )"


Anybody let me know where to modify at nopcommerce22? thanks a lot!