How to change proxy for httpclient?

Question

Hi, from this codehow do I find the address and port?

can i get the data here

then paste in the proxy info like this?

however , then I cannot access the internet..

Is there a simple way I can manually generate the ip address and port during the run of the code? where do I need to get these list?

because, I want to set up proxy for httpclient when craw web but I'm stuck.

Thanks you!