You can find info about Dutch trains on www.ns.nl. What you need is info about international trains. Strangely enough this part of the site is not available in English.
Travel from Amsterdam to Brugge is as follows;
Amsterdam to Antwerp, change train for Brugge. Trains leave Amsterdam Centraal station 26 mins past the hour. They run every hour. Journey time 3 hours and 37 mins.
--- “I travel not to go anywhere, but to go. I travel for travel’s sake. The great affair is to move.” Robert Louis Stevenson
You buy your ticket from the international counter or the counter that says Belgium, or something similar. The international counter charges a booking fee. and the Belgium counter charges €0,50 extra.
Best is to buy from the machines. They have an English version. This is a link to the demo.
No need to buy first class, second class is very comfortable and a lot cheaper.