Music Powerpoint Presentation

How do I add music to my entire Powerpoint presentation?
I am trying to add music to the whole presentation, instead of just one slide.
1. Open PowerPoint and display the slide where you want the music to begin. On the Insert menu, point to Movies and Sounds, and then click Sound from File. Locate the folder that contains the sound file and then double-click the file you want.
2. When a message is displayed, click to play the music or sound automatically.
3. click the sound icon , right-click, and on the shortcut menu, click Custom Animation.
4. In the Custom Animation task pane, click the arrow on the selected item in the Custom Animation list, and then click Effect Options.
5. On the Effect tab, under Stop playing, choose to keep the sound file playing for several slides, click After, and then set the total number of slides the file should play through.
6. If you do not want the to appear during the show then drag it outside of the viewing area.
Tips:
Free and easy method:
Use PPT2Flash http://snipurl.com/ppt-swf to add backgroud music with one click. Use this free trial one, you also can insert Flash for free.
It saves a lot of time for my daily work.
Hope it helps!
How to put music and videos on a PowerPoint Presentation