All I can say is it takes time and practice. A lot depends on whether you are a natural when it comes to playing the instrument. For myself, It has been a life long journey and I still suck, but I play for my own enjoyment and that is worth it all. My son is a natural on the guitar, totally self taught and he rocks!
I would say to definitely learn songs using tableture notation. This will greatly speed up your learning curve and enjoyment of playing real music. You can search for tabs on just about any music. Good luck!