you basically have to find an exchange that is offering FIAT payouts. Depending on where you live, it might be easier ot more difficult to do so. Some countries have very stirct rules on cryptocurrencies and in others its a breeze. China for example it's getting quite tricky to get any FIAT into crypto's, because the government doesn't want its Chinese Renminbi to leave the country, in the US and Europe from the other hand regulators have not taken any serious actions yet against FIAT deposit/withdrawls. What I recommend is that you do a google search, like "Sell BTC/ETH in [INSERT COUNTRY]" - you'll probably get a few exchanges listed that will serve your location. You'll have to submit some documentation for the KYC process (they need to know who you are) and after that you can easily buy or sell cryptos and convert them to FIAT or vice versa.