My go-to when I started in Deep Learning is Stanford's CS 231n course http://cs231n.github.io/, the lecture notes are amazing. It was instrumental when I first dove deep into Deep Learning and helped me understand all the components needed to make Convolutional Neural Networks(CNN) and Neural Networks(NN) work. I first read this and watched the lecture videos. This course was a great primer for me to understand the content and theory in Goodfellow's Deep Learning book.