Just to add to your frustration, where she says you have to have the oven preheated, I also do that recipe from a cold oven. You might need to check to see how long it actually takes your oven to reach the 450°F. You will need to add that time to the baking time.
I like to do it with a cold start because it eliminates some of the danger of messing with a preheated baking container. And I find that the resulting breads are similar.
And please take a look at the great videos at Bread Baking Instructional Videos and Baking Supplies.
You need to bake the last 15 mins uncovered to get a good brown, crips top crust.
My one problem in baking in my cast iron Dutch Oven was that the bottom was getting somewhat burned. I now use a baking sheet upside down under the DO. Seems to give it an air cushion.