Ignore the newbie pal, Pre-Spray Gold is bob on for wool if you want to be on the cautious side. The first thing you will need to do is check to see if it's hessian backed and I would not even clean it tomorrow if it is because you could be just wasting your time until you know how to tackle browning and get some browning prescription (search browning stains, their is loads of info on here on how to tackle them). Take an air mover if you have one too, the faster you get it dried out the better. Find out when the leak was, if it was recent make sure the underlay is not still soaking wet before you start.