Best way to make money from bitcoins is to buy them and then forget about them for sometime. Good luck!
How do I know when to sell and where exactly do I sell ?
It is like impossible to tell how the price will move or when the price will hit the high/low. But if you are confident in bitcoin, you may buy some bitcoin and wait for a few years. Consider that a long term investment and don't invest more than you can lose.
Any reputable exchange will work, bitstamp, btc-e, coinbase, localbitcoins, etc.