You learned how to make an empty file. On Unix touch does this, and it also changes the times on the file. I rarely use it for anything other than making empty files. On Windows you don't have this command, so you learned how to use the New-Item command, which does the same thing but can also make new directories.
For the price of most other course's PDFs only, you can get the full PDF for this class and 2 videos demonstrating the whole book for both Unix/OSX Terminal and Windows PowerShell. The course is self-paced so you can go through it any time you want, as many times as you want.