amsterdam airport to city?

does anybody know how do i get from amsterdam airport to the city central station? is it easy to find the train from the airport? is there a train all the time?how much does it cost? thanks
i am going to arrive at 20:30 at night

The airport has its own station, and you can get a train straight into Amsterdam Centraal Station. Enjoy Amsterdam - it's great!

www.amsterdam.info/airport/train
will give you all the info you will need

Get a train straight into the centre!

theres a tube station in the airport that goes to the centre of amsterdam.dont know the cost but its not much .the dutch speak very good english so if confused just go and ask in a cafe or something.they must run late because i was leaving amsterdam for the airport at about 9.30

In the arrival hall there is a booth where you can buy your ticket for Central Station. It is cheap, maybe a few euros.
Then follow the signs for the train, go down a level and make sure you stand on the proper platform.
The trains are quite frequent (maybe at 20.30 every 30 mins)
Get off at the last stop. It's very easy.

The train station is right at the Airport, just follow the train symbols. Trains to Amsterdam Central station are departing six times per hour until midnight at minutes 07, 16, 29, 37, 46, 59. After 00:30 the frequency will be limited to hourly night trains. The travel takes 17 to 23 minutes depending whether you caught a direct train or one with two intermediate stops at Lelylan and Sloterdijk. The ticket is €3.90 if purchased from the yellow self-service vending machine or €4.40 if bought at the NS counter.
Trains to Amsterdam-Centraal are departing from platform 1-2 at minutes 16, 29, 46 and 59 and from platform 3 at minutes 07 and 37. Make sure that the train destination on the information board shows Amsterdam Centraal since there are also trains to Lelystad, Nijmegen or Utrecht departing from there which do not pass the Amsterdam Central Station (CS) but go via Amsterdam-Zuid.


Source(s):
http://www.ns.nl/cs/Satellite/travellers

It's very easy - you can get the train, the name of the main station in Amsterdam is Amsterdam CS, and there are ticket counters so you can buy your tickets right there. It's a very convenient set-up, actually.