There are many people in your life to be friends. There are only a handful you can trust and would be able to talk heart to heart, and walk through life's situations with you. These are call true friend. But before this can happen, you have to be true to people in order to find true friends. Of course there are times of betrayal, but there are also great friends that will surface...

find someone who has common interests as you, one who is loyal, and someone with whom you can share mutual respect. oh and someone who likes to give hugs helps too hahaha :P

chat and talk clearly , don't lie or compliment
respect all people ( nation - religion - old - job ...etc )
try to understand friends and their customs
trust them and make them trust you

I don't think they can be 'true' friends because you haven't met them face to face, but it's good to communicate with people from all over the world.

I would put my answer together from the answers by Jura and Calix Reneau:
when we act as friends, we will receive friendship. But we should not claim friendship.
Friendship is always a gift.

One more: friendship is like a flower, it needs care and time to grow. It may be difficult to find friendship via internet only, as internet is fast changing and we meet new people every day. But if we are patient and slowly and steadily maintain special contacts, there may be friendship over long time.
In the end it might be important just to meet in person.