It's a little confusing, but playing around with it I was able to understand it. First of all, there's a Start button at the bottom of the right menu. Hit that

It's a little confusing, but playing around with it I was able to understand it. First of all, there's a Start button at the bottom of the right menu. Hit that and you will see that big color gradient sort itself. However, that massive square is useless for seeing what's going on. So instead change the size to its lowest (8) and the delay to something like 400. Now what you've got is 8 randomly-sorted columns. When you hit Start that algorithm will start sorting them each in parallel. You can just look at a single column and see the colors getting swapped. The darkest color moves to the top very quickly. This is a feature of how this particular algorithm works. What's the point of the big square? Well, for one thing it's an interesting way to compare algorithms. Go back to the settings for a large number, a very low delay, and check off two other sorting algorithms, say Comb Sort and Heap sort. Hit Start and you'll see three very different approaches to sorting the columns.