I heard that I can exchange Bitcoin with someone near me such as my friends but how can I exchange Bitcoin with them? 
if you want to exchange bitcoin with your friend you need to use https://localbitcoins.com/ this site would automatically track your nearest friend or people.https://localbitcoins.com is used for when you DON'T have a friend with bitcoin. A much easier way to trade with your friend is to simply pay him with cash and asking him to send the corresponding amount of bitcoin to your address. No middleman involved.