Aruna:
I have never used (or seen) this website before so I have no idea. But what I do see is that they are quoting all their fares without taxes and charges.....which add up to hundreds of dollars per ticket. Be careful as lots of websites price this way and then its way more than you think.
There should be some codes involved with the tickets so you know the conditions of that ticket as to ability to change etc. On my international tickets, historically I price on a website and then ticket through an agent or more recently directly with the airline. You can hold tickets for a day or two with the airlines if you see a fare you like and keep shopping and then ticket if you find its the best price.
I know the trepidation about using websites. When I went to Hong Kong years ago I used an agent I found on the Hong Kong govt website for a promotion they were running. (BTW if anyone is going to Hong Kong you should check out the deals on that website!!!) I had r/t from NY, 9 nights 4 star, transfers to/from airport in HK, half day tour of the city, and travel insurance for $895.

I used a credit card in case this was not legit so that I could fight it. I got to the airport and amazingly the tickets were fine. When I arrived amazingly there was the person to pick us up. I actually got the the 4 star and into a decent room. I was amazed that such a cheap price was real. My point: you never know....sometimes internet deals are really really good and no hitch involved.