Select an item from the drop down box. See if you can figure out what the original order is. If you want to challenge yourself, you can drag and drop the sentences to make them read the way you think the paragraph should. Then hit "go" to check your order against the original. If they match, the word "Awesome" appears on the screen. If not, a try again button will appear and you can go back and think some more. If you get frustrated, you can reveal the original by clicking "view original".
Because editing other people's writing is not the same as editing your own, after you have tinkered with some of the examples, tinker with some of your own.