Controlling your dreams takes a lot of practice. It requires patience and a basic understanding of sleep. I once had a lucid dream but that was on pure luck without even knowing what they called a controlled dream. If you are getting close then good for you, just have patience and you'll master it. Basically, you teach your brain to allow you to be fully aware of you being in R.E.M. Sleep without waking yourself up. That's why many fail when they get close because they get super excited resulting in us exiting R.E.M. Sleep. It's basically tricking us into being aware of being in deep sleep or a more simpler way of putting it, being in the middle of napping and R.E.M. Sleep.