Do you men to ask which BTC website/exchange is trustworthy?

Well, if you are buying Bitcoin or any other Atcoin (eg. Ethereum or Ripple or DashCoin or Lite Coin or whatever) for long-term investment, then you don't keep it with the exchange , no matter how reputed it is. Because exchanges are prone to hack attacks/bankruptcy etc.
Better to buy them from CoinSecure/ZebPay/LocalBitcoins/UnoCoin and then transfer them IMMEDIATELY to an offline wallet.

However, if you are in there for short term trading, then after buying on any of the Indian exchange, transfer your Bitcoins to a reputed international exchange like Bittrex/GDax/Poloneix/Kraken etc. and then do the trading there.

Which exchange do you choose should depend on :
1. whether the exchange supports the cryptocurrency you want to trade in
2. deposit/withdrawal feels
3. transaction charges
4. Other factors like support response time, UI/UX etc.