How to become a singer?

I've loved singing since I was young. I play the flute, but no other instruments. I have written quite a few songs, but only the lyrics. I can read music but I don't really know how to write it, or what to put behind the vocals. How can I become successful with the only skills I have right now? What other skills will help me become successful and how can I be proactive? I'm 19 and I pretty much only sing for myself right now.