Actually, the one in Amsterdam isn't quite between the Krasnopolski and the station - it's the other direction

If you follow the tram tracks from the station straight up the middle, you will eventually see the Holland Casino on your left side. Hopping on that tram might be better, though... LOL... or grab a cab, it's only a few minutes by car.
You will need to obtain a membership - and then pay an entrance fee (7 Euro last I remember, but it could have gone up).
They have a few other branches in other cities, as well as the airport, and they are the only licensed full casinos in the Netherlands. Alternately, you could go into one of the arcades and play either Dutch fruit machines, or machine-based roulette, but for low stakes.
The casino at the airport is not a good idea unless you feel like throwing away your money, or bucking higher odds (the roulette is double zero and the minimum bet is 10 Euros). The slots are also quite tight there.
(edit - CheekyMonkey's got it!)