If you have a site with a fixed IP then try something like this:
'{\"map\":{\"\":\"193.99.144.85\",\"www\":\"193.99.144.85\"}}'
If you already own a .com or similar, you may try:
'{\"translate\":\"www.example.com.\"}'
(don't forget the dot at the end!)
If you have only a dynamic IP, e.g. a PC at home running a web server, or a NAS, you may need to register with a dns service and figure out how to dynamically update the current IP (many WLAN routers offer an option for updating the IP to the dns service). One of the free services is dtdns.net, and your entry would look like this:
'{\"translate\":\"my_webserver_at_home.dtdns.net.\"}'
(again, do not forget the dot.)