Good for you man! When I started coding for the web at 23 years old some pople told me I was too old to be a coder. 14 years later I'm still coding and run my own company. It can be difficult to make the transition though, but with enthusiasm like that you should be able to do it.

The best thing that you can do is to teach yourself on some practical projects. I always find that it's way easier to learn a new coding language when I have a practical application to work through. Find something that's relatively simple, but that interests you in having for your own use. Then find tutorials and buy books that will help guide you through the basics and start putting together what you need. If you're a complete beginner to coding, then a basic introductory course or book would not be amiss as you'll need to get the base concepts down.

As regards which language is best, I'll leave that to the mobile experts as I specialise in web apps.

Good luck - I get a kick out of seeing people so ethusiastic about getting into coding.