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.