Here are some great articles and books that I've enjoyed which teach you more about how to use typography in digital design. If you're interested in learning more and getting an in-depth understanding then look no further.

Books

Thinking with Type, Second Revised and Expanded Edition: A Critical Guide for Designers, Writers, Editors, and Students (Design Briefs)

The Elements of Typographic Style

Just My Type: A Book about Fonts[ JUST MY TYPE: A BOOK ABOUT FONTS ] by Garfield, Simon (Author ) on Sep-01-2011 Hardcover

Articles

https://medium.com/product-design-ux-ui/26-digital-typography-rules-for-beginners-a04c6a5aaff3#.10tgnccvf