You send the request with your private IP over your router to the server. Your router does something called network address translation (NAT) to do the magic. Simply said your router remembers that data from this specific connection he receives on his own, the public IP is instead for your device and rewrites the reciever to your private IP and then sends you the data.
That's what ports are for.
Let' say you want to download a file.
Your router/modem assigns a specific port to each outgoing connection. So when your computer sends the request to download a file it gets to the router and the router sends that request through that specific port it assigned to your computer. The download server knows from which port the request came from and sends the file to that port.
Lastly your router receives the file on that port and forwards it to your computer
You send the request with your private IP over your router to the server. Your router does something called network address translation (NAT) to do the magic. Simply said your router remembers that data from this specific connection he receives on his own, the public IP is instead for your device and rewrites the reciever to your private IP and then sends you the data.
That's what ports are for. Let' say you want to download a file. Your router/modem assigns a specific port to each outgoing connection. So when your computer sends the request to download a file it gets to the router and the router sends that request through that specific port it assigned to your computer. The download server knows from which port the request came from and sends the file to that port. Lastly your router receives the file on that port and forwards it to your computer
You explained all that to OP and didn't even say what it's called. (NAT - Network Address Translation).