post offices in Amsterdam

eyup peeps jw if anybody would be of any help.

Am going to amsterdam at the end of the month and wouldn't mind posting some treats back.
Just wondered if there were any post offices or anywhere to buy post stamps in amsterdam?. (preferably towards to near the centre of the dam).

Yeah, I'd be interested in hearing about this too. Any tips? Can I go buy stamps quite easily, then prepare my package to post home and drop it in a local post box?