The exchange to use, depends on the country you're in. and in order to sell the coins, you have to send them from the paper wallet to the exchange. i would advice downloading the btc wallet and try scanning it again and once it works, you create an account in an exchange suitable for your country, you send the coin to that exchange and exchange it for money in your currency.
If scanning doesn't work, you could try editing the QR code to magnify the image.