There is an important point to be made here—not to put you off Hot Potatoes, but just to make you aware.
Hot Potatoes quizzes are great fun and very useful as homework, consolidating what's been taught in class. However, they shouldn't really be used as assessment tests—crafty children, over the years, have found ways to get the answers without thinking too hard. They'll press the back button for instance, if they get one wrong, and allow themselves another try. Some of my students also have discovered that if you click on Hint, you get one letter of the word. When the Hint button is pressed again, you get another letter—until you get the whole word given to you. If you want to set a test in Moodle that you don't have to mark (and who wouldn't?) and is pretty much hack-proof, then you should use the Moodle quiz—as we shall be doing next.