Because we're using multiple resources, and few of them can keep up with things in the real world, you'll need to be agile. Here are a few notes to start with:
All html code should be html 5, and include a validation button. In general this will be easier than sample code- but you'll need to know what to do to make your code html 5.
Your instructor may have programming/coding standards that differ from examples online and in the book. There is getting things to work, and there is clean coding. You'll need to do both, to your instructor's standards.
Understand there is a difference from just opening a file with a browser (i.e. double-clicking it, or choosing file, open...) and RUNNING it from a webserver (where you go to an http:// address). An html file will look the same in both cases, but php will not run if opened as a file.