Add a new entry as shown in figure below
Save settings & reboot the router. Now you can control your device from web browser like this:
How about if I don't know my Public IP Address?
You can have many ways to get the Public IP address.
You can get it from the router status page as shown in figure below:
You can get Public IP address from website as shown in figure below:
All the above step must done in local network, how am I to get the Public IP address if I'm not within the local network?
To get Public IP address from outside, you must set the DDNS (Dynamic Domain Name System) to the router or device to be control. Normally we set the DDNS to the router.
You must get a DDNS account before you can set to the router, here listed two common use service provider.
DYN: http://dyn.com/dns/
No-IP: http://www.no-ip.com/
DYN is not free any more, you can go with No-IP if your router support No-IP service provider.
If your are using D-Link router, you can use the dlink ddns: https://www.dlinkddns.com
As shown in figure below is an example on how to set the DDNS account to the TL-WR1043 router.
After configure the DDNS settings. Save & reboot the router.
Done! You are ready to control your device over internet. I use http://ediy.dyndns.org:455 to control my device.