Very Noob ... browsing HDD and selecting directory

I am trying to build a window in my app that allows the user to browse the HDD and select a directory.

Once they select the directory they would click a button on the window that would load the selected directory into a variable for the app. and close the window.

I am just starting out with cocoa. I've been looking through the documents on the apple dev center, but can't really find anything about how to actually make this happen.

any help and/or direction is greatly appreciated.

thanks