Question about Lost In Beta's Preloader Tutorial

I followed it, but I don’t understand where the numbers come into play? Or how to work it after I get all the stuff done. I have everything done, up until the part where I have to make my movie in the 3rd frame in the ‘actions’ layer.

I inserted a movie clip in that 3rd frame and nothing happened. It didn’t preload anything. Whats wrong? Do I just start making the movie in Frame 3 of the ‘actions’ layer or do I make them a movie clip?