I use Broad Band internet line. I want to use wifi. How is it possible ?

It depends on what are u using, if you are using a PC then you have to buy one wifi device. If you are using a laptop then it is generally present in it what u have to do it just on it and connect to your smartphone rout.

You will need a wireless router, http://www.wikihow.com/Set-Up-a-Wireless-Router

purchase and install a wireless router.

You need a wireless router.