Yes you must publish the file in Flash. File -> Publish. Then in Dreamweave you import the .swf file that was published. That is if the only thing in the flash movie was the button.
you need to publish (shift+f12) to get a .swf, which is then embedded in HTML through DW…
if it is the size of the movie which is the problem, then simply make the stage the size of your button before publishing (very little white space outside your button)…