It's horses for courses really.
Some people learn intuitively by trying things out, others need instruction to give them the basics to work from and to have someone look at the shot your taking and then suggest a way to improve it.
I learnt a lot years ago by having a fully manual film camera, then I learnt even more with my first film SLR and now I'm still learning by trying things out on my DSLR.
But if I had time and money, I would like to do a more advanced course to hone my skills.
btw: don't worry about the "funny little graph", that's just the light levels hitting the sensor. Ignore that till you know more about it. I don't ever use it myself.