I would suggest going through the Fast.AI course [1]. It's an excellent course to learn more about DL in general, and some of torch API. The downside is that the course material was produced when PyTorch was still at 0.3, so some of the API has changed since then.

[1] https://course.fast.ai/

There are several good books written or in development, but if I had to pick one right now, I'd point you to this one: https://www.manning.com/books/deep-learning-with-pytorch

The best resource I've found are Udacity's Jupyter notebooks: https://github.com/udacity/deep-learning-v2-pytorch. Start with intro-to-pytorch.