Ask HN: Best way for a beginner to learn Networks and Async Programming

Hello averybody! I've just finished Harvard's CS50 and MIT's 6.00x courses on edx. They are introdutory courses on Computer Science (the first one in C and the second one in Python). I work as a P.O in a project, and attended this courses to understand better what my team does. The courses are excellent, and now i want to expand my studies in the area. In my project, we have code running on several machines, and i would like to understand better how they talk to each other (networking, event loops, async programming, basically). I`ve found this course https://class.coursera.org/posa-001 (Pattern-Oriented Software Architectures for Concurrent and Networked Software), but it requires a more solid background on programming. Any thoughts, sites, books, keywords, courses about the subject?