Almost certainly when you told people you were going to Amsterdam you were given a wink, a nudge, and a sly smile because anyone who knows anything about Amsterdam knows that Amsterdam allows folks to buy and smoke that wacky tobacaky, dope, herb, mary jane, ganja...yeah, it does and it is cool.  Coffeeshops are where you will find marijuana and hash to buy, but you don't have to smoke it there.  You can take it with you to other coffeeshops, smoke very discretely in a relatively isolated location, or in your room if you were wise enough to get one that allows smoking. If you decide to smoke outside keep in mind that while the Dutch tolerate soft drugs they are not happy to have you puffing a fatty and acting a fool in front of their children, so be discrete. Don't be stupid or rude and you should be OK. 

For those who dont smoke it may be possible to buy some space cake/cookies and cannabis tea.Take care with the cake and follow any reccomendations like only eating half and waiting an hour before finishing the rest as the effect can creep up on you 

There are over 300 coffeeshops throughout the city each offering their own vibe. Some places that get good recommendations include Barney's, Abraxas, Grey Area, Homegrown Fantasy, Stix and Tweede Kamer. Do a search for 'amsterdam coffeeshops' for maps and locations of most of the coffeeshops in the city. If you discover a shop you find you want to hang in and smoke, great.  If not, buy some and get a pipe at one of the ubiquitous shops; a small metal one can be purchased for under 5 euro.  Anytime you spend any time in a coffeeshop buy something to drink, especially if you bought your pot elsewhere. Those who frequent coffeeshops need to do all that can be done can to keep these unique and wonderful coffeeshops open for business.

If you use some common sense, you'll find that many bars will allow you to step outside and have a quick smoke without much hassle.  If you have a question regarding whether the bar will allow you to smoke pot, just ask.  New laws prohibit tobacco smoke in the bars but not marijuana.  Most bars are very cool and may just ask you to step outside.  Don't expect them to join you though.  While folks in Amsterdam smoke, not all do and most smoke less than the average tourist.  You can also step into the bathroom and fire up a bowl for a few hits without much hassle. 

Amsterdam is a great city for many reasons, the coffeeshops are just a small and very enjoyable part for many adults.