The following link is the graphical representation of the networking done in my home.
I have a DLINK DIR-600L Wireless router which is connected to modem via a switch. As this router have DDNS service enabled, I registered a domain in 'dyndns.org' and configured the router.
Then I setup a webserver under my router network(3) and setup the port forwarding in router from ip '18.104.22.168'. Now I can access the hosted website anywhere in my home in ip address '192.168.0.2'. Then I configured the DDNS to ip '192.168.0.2'. The problem is that this dyndns domain name can only be used inside my home network(1). I need to access my site from anywhere in world via internet. How can I do this?