This is standard with instruction-writing. The idea is to get the reader's full attention. Special notices . In these instructions, we have several notes that call readers' attention to special points such as how to get a POP account, the syntax of a POP account, and so on. We also have two warnings which in the style used in this online textbook and its examples are used for situations that could damage data or equipment or cause the procedure to fail.
Instructions often use some form of highlighting such as bold for menu, option, and button names.
These instructions don't, however. When you write instructions for computer software, you can use screen captures of the software interface at the various points you use it. After that, just paste the image into your document. That completes the comments for this example.