I just used it (and managed to screw myself ) just two days ago

You check in the usual way then it says "do you want to pay 'x' for alternative flights?" you are shown what options you have

It was going to bill me 25 dollars (Silver) and I picked the flights all excited because thats what I wanted

STUPIDLY..........I didnt realize that the flights I was going to get ...........were for july 5th, when I wanted july 6th (in other words original reservation was suposed to leave at 6:45 AM.........well..........it offered me 11:00 AM on july 5th!)

this of course took me a while to a) realize what had happened , b) call and beg them to help c) straighthen it out

By mere luck, the agent managed to get me my originals flights! phew