The use of background music gives suitable emotional coloring to your slideshow and brings more pleasure to your friends, family and many people who will watch and enjoy it. Unfortunately Picasa does not have the option to add background music to your Web Album slideshow, but you can save the slideshow in Movie Presentation and add a video to YouTube.
In Picasa, you can only use music that is in MP3 or WMA file formats.
Note: Picasa doesn't support a smooth, continuous playback of music loop tracks.
If you choose Melody Loops music, you have a great possibility to customize your audio file with Longoloops tool. When you adjust the length of music track it is important that you know each photo shows about 2-3 seconds, therefore you will need music file's length about 1 min 30 seconds to a slideshow of 30 pictures.
There are two ways of adding music files to play on the background of your slideshows
Method 1: Adding music to a particular folder or album
Using this method you can set each folder or album to be accompanied by music. However, the number of music files that could be played during slideshow are limited to one.
Select the folder or album.
Right click on the name of the folder / album and in the dropdown menu, select Edit Folder Description.
Check the box in front of Music - Use music for Slideshow and Movie Presentation and click on Browse to choose music file.
Click on the icon to play the slideshow.
Method 2: Adding music to any slideshow
Using this method you can set any Picasa slideshow to be accompanied by music. Select a folder with music files you want be played by turn during slideshow. With each replaying of the slideshow, the music will continue to play as normal until its end and start another track in the folder.
Select Main Menu -> Tools -> Options.
In opened window click on tab Slideshow.
Check the box beside Play music tracks during slideshow.
Click on Browse and select the folder with music files.
Thus selected music will play every time you start the slideshow.