In the “Prompting for the Visitor’s Name” section, contextually, the reader has just created the treehouse project. As they look for a prompt to which file to edit, they see, in the blue highlighted section,
FirstStepsWithRust/hello_yourname/src/main.rs
This appears to be a delightful convention that allows the source to be downloaded directly-- awesome!! – but the reader was in the treehouse, not hello_yourname. A small info box that explains the convention, and how to (perhaps) focus on the filename after src for their own work may be helpful.