But is there a place where we can buy and sell bitcoin instantly?
You can use some exchange sites if you want to start trading with bitcoin instantly. You can try to use bitstamp.net, coinbase, btc-e.com and there are a lot more of it just google it out. And most of them are capable to buy your bitcoins instantly and as well as selling some bitcoins. There are also some people who are using virwox.com
Stay away from virwox.com. That is not a good exchange for Bitcoin trading. Also stay away from Coinbase. The IRS are after them and they are demanding that they hand over the transaction records of all their customers. That is an invasion of privacy and if some users are caught evading taxes, they will be prosecuted. I believe Coinbase will also be prosecuted for being an enabler.
Bitstamp was hacked last year with $6m stolen from them. The same with Bitfinex, it was also hacked and some money was stolen. That leaves us with BTCe. The owners are anonymous but have been trustworthy so far.
VirWox charges a lot, and there is a very complicated and meaningless interface design. I certainly do not recommend it. I used it for another purpose, but it melted my money.
I don't see and never use virwox I have read some news of it so since when I know some information I stop and never use that there is a time that pursue me to use but when I read some bad feedback about it I never continue using that.