If you want to get an introduction to building neural networks and deep learning, this online book is a good start. If you don’t know Python, I recommend to learn at least the basics of Python.
After you read the book, or most of it, you’ll want to try yourself. The book has examples, you can get them from github. But a real next step is to try Google’s Tensorflow. The Tensorflow tutorial here follows most of Michael Nielsen’s book. Have fun building your first deep learning neural network.