Setting a url to a button

Hey, its been a while, its good to be back at Kirupa - th ebest place for flash hunters:) so my question is very simple and I am sorry if I am the 1298th person to ask it but couldnt find an answer. I just downloaded a flash CS3 trial and I am playing with it. What I am trying to do is to set a url to a simple button I created - where is the AS for this? how shall I do it? Such a simple thing seems so difficult:| Please help!

many thanks!