Will u please tell me how can I track a caller
Or
To track the network area of particular number

You can't

You may track a phone that you own if it has that application builit into it. For example, my work phone ( and all of our companies work phones) can be tracked.

So if you own the phone, and paid for the tracking service and have that application in phone, you can.

Search for Google Latitude, a tracking program for cell phones.

http://www.google.com/latitude/intro.html#dc=gh0sla&utm_campaign=en&utm_source=gh0sla&utm_medium=ha&utm_term=google%20phone%20tracker

But this needs to be installed on the phone and it allows you to view the location also

I may be wrong but the OP said track a caller, hence this isn't his/her phone they want to track.

Beyong using the area code (assuming it's not been spoofed) is the only way you can remotely tell where the caller's phone number was issued.

Ie: If the number is 511-555-5555 then you can look at the 511 area code to determine a general location. However this always doesn't because the owner of the phone could move and keep the number.

Ie: I am orogiannly from 3 hrs north of where I live now. My area code is xxx but if you were to search for it, it would show you I live in location A (or vicinity) but I actually live 3 hrs South of there.

Beyond this, you're pretty much stuck!