If you are mentioning about a static IP for internet (WAN) then you need to ask BSNL to provide you with one. If you are using a home plan they won't provide you it is only for business plans. If you mean static LAN IP just go to network connections go to RUN type cmd and type the command ipconfig take note of your IP address assigned by the DHCP in your modem. Now go to network connections go to the properties of the Local area network connection -> Internet protocol properties and enter those IP addresses.
As for port forwarding go to your modem setting page (type http://192.168.1.1/ or http://192.168.0.1/) in you browser on the left side (usually) locate an option named NAT create a new rule Set the external IP address as ALL and the internal as that of your computer, enter the port number select a protocol (TCP or UDP) and save it.
Thanks for replying..
i had worked it out.
IDK if am assigning WAN or not.
Step 1 : goto adapter settings->properties
Step 2 : Select use the following IP address
IP: 192.168.1.XX(anything other than 0 and 1)
Subnet : 255.255.255.0
Default Gateway : 192.168.1.1
Step 2: Set DNS to use open DNS