I think that trying to understand an open source project is excellent advice for someone who already knows how to code and wants to get to the next level, but not for someone who is just starting to learn how to code. When you're starting to code, you need to start with very small programs and work your way up to bigger ones, not by trying to navigate through thousands of files filled with millions of lines of code. Understanding vast extents of other peoples' code is something that even experienced programmers struggle with.