Challenge #3

$ echo 42 > SUPER-SECRET.txt
$ git add .
$ git commit -m "Shhh!"

Notice that git commit -a doesn't work here. This is because git treats "untracked files" differently. They're not part of your repository (yet), so git assumes you probably didn't mean to include them. This gives you a chance to be explicit. Do you want to permanently ignore the untracked file, or actually include it version control?