Correcting poor posture (head forward)

Your best bet would be consult your Doctor or Chiropractor about this as they would be able to tell youth best exercises to correct this problem.

Try the suggestions in this article, hope it helps Good luck!
http://www.collective-evolution.com/2014/07/07/6-bad-postures-that-are-ruining-your-health-and-how-to-correct-them/

1.Some exercise can be easily found on google to enforce & train back muscles
2 Not very many people realize it but in fact it’s critical to have a desk and chair of proper height. The way to tell can also be found on google. As a 193cm-guy, I seriously recommed it, which makes me feel lot better and sit in right posture automaticly.

Yoga changed my life in this regard. I didn’t even realize the pain I was in until I learned to roll my shoulders back and drop them down.
If you can get into a good Iyengar yoga class (this type focuses on alignment) I am sure you would be happy with the results.

Ballet always helps me get back in line. I Zumba too, which helps, but if you choose to try Zumba or a class at a gym like boot camp (men like that better) be warned the instructors tend to lean forward! It drives me crazy. If they have dance backgrounds they usually don’t, but that’s rare. I stay back straight no matter what they do.

Yoga, as @Judi suggested, is probably your surest bet at a gym to have an instructor who does positions with the back straight. I happen to not like yoga, but so many people live it. It will help develop the muscles so it’s not tiring to sit and stand straight.

If your spine is actually curved that is a different problem, but I believe at least some of it you can probably improve with exercise. And always correcting your posture when you realize you are slouching. Stomach in, stand tall, shoulders down.

Try Garudasana to start.