They jump right in, giving you the needed settings for your php.ini file to get the examples to work (mainly for the file uploads). They explain what a file upload form looks like and what some of the potential error codes could be.
The code comes next, showing a simple file upload form taking in the file, moving it off to another directory, and if there are errors, displaying them. The next obvious step up from a single file upload is the multiple file upload, and they show how to use PHP's form handling of arrays to accomplish this.
Finally, they include a simple little script to read the directory the files are in and display the information about them (like size file, name, and modified date).