Here are some getting started resources:
A quick-read ebook: https://www.mathworks.com/content/dam/mathworks/tag-team/Objects/d/80879v00_Deep_Learning_ebook.pdf
and video on CNNs: https://www.mathworks.com/videos/introduction-to-deep-learning-what-are-convolutional-neural-networks--1489512765771.html
while deep learning focused on images in the past, we now have examples for image, signal, text and audio here: https://www.mathworks.com/help/deeplearning/examples.html