Join a Club

It can be a church group, a charity organization, a hiking team, a toastmasters debate group. Find some sort of group that is large and has both boys and girls in it. That way you can have all sorts of planned events to go to and will be mingling with lots of different people. You'll have guys to talk to to build friendships, and girls to get to know. Because it'll be a friendly group, it'll make it easier for you to talk with the girls and be friends with them.