The best way to get there is undoubtedly to fly to Amsterdam then get the train. You can fly from Leeds-Bradford with:
Places to stay
Grand Hotel Central (not cheap, but near the station)
Rough Guides guide to Amsterdam (click on Amsterdam under Featured Cities)
The ground is quite a way out from the city centre, although the transport options are pretty good. You can get a tram, or alternatively there's a train station next to the ground. Click here for a site about the ground, including instructions on how to get there. There's a map here.