Well, one method is to first buy Bitcoin from any of your local exchanges and then exchange the BTC for XRP on another crypto exchange, such as Changelly.com or Poloniex.com.
You may also sign up with an Indian exchange which sells Ripple. Some I’ve seen which offers XRP markets are BuyUcoin.com, BTCxIndia.com and Koinex.in – however I’m not endorsing any of these exchanges. I have never used them and I haven’t done any serious research into them either, so please do your own due diligence.
I would also say that you should study Ripple to ensure that it’s right for you… It’s highly centralised, to the point it can’t really be considered a true cryptocurrency, and the Ripple owner / company owns between 20 and 60% of all XRP. It seems to me that the Ripple network may be of value to banks but I’m not convinced the coin will be of value to individual users (apart from speculation purposes). Just my 2c on XRP.