In flash there are 4 types of sound options in the synch pull-down menu in the Sound Panel: Event (default), Stream, Stop, Start.

You also have an effect choice to fade in or out, or you can do this yourself if you press the edit button in the properties panel which takes you to the sound editor,where you can cut your sound. When using multiple sound tracks you will need to put them on separate layers of your movie.

You can import MP3 files, you can also import AIFF files (Mac) or WAV files (PC).

To get sound in, simply go to File>Import> Import to Library and select your sound file. It will go in the library.

When you put a sound in the timeline, you simply drag it out of the library to the timeline and then go to your Sound Panel and choose the Synch type and if you want it to loop and if it loops, how many times you want it to loop. The maximum is really high (like 999 times). If you want it to loop throughout your movie, you can enter a large number (it won't allow you to go too high).

Event: event sounds play when the frame that they exist on is encountered. They will not synch to animation and will play until the end of the sound independent of what is happening on the timeline.

An event sound can be used over and over again in your movie and only needs to load once, so it is a real file size saver, and is very useful tracks that are large that loop (such as theme music). Or it is great for buttons (they repeat the sound often).

Event sounds are funny. Sometimes they are triggered by your playhead just passing by the movie clip they live in on it's way to another movie clip on the timeline in another location. You may get the sound mysteriously playing. If this happens, make sure the movie clip is stopped on frame 1 and the event sound is moved to frame 2 or 3 of the timeline of the movie clip that it lives in.

Stream: Stream sounds lock to the timeline they are in and attempt to synch up with animation. You can hear these while you scrub the timeline (unlike an event sound, which you will not hear until you test your movie or hit Control/Play). Stream sounds load as they are playing and if the same sound is encountered in your movie at a later time, it will need to reload as it is going again, making your file size larger. It is best suited for tracks where lip-synching is occurring or for areas in your movie that need to synch with a sound effect.

Stop: Stop sounds simply stop the track that is currently playing from playing. It stops a specific sound in it's tracks.

Start: Start sounds are like event sounds in behavior, with one difference, it will not play over itself if it encounters itself on the timeline again. This is useful if you use an event sound in lets say a frame loop in a preloader and you don't want it to play over itself. It is also great for buttons, where the sound is long enough that the user will roll-over the button before the sound is finished.

When Publishing sound for the web, make sure if you are using speech to set the export to MP3, and the kbps to at least 20 or 24, preferably 32 and choose mono. This will give decent sound quality for the web. If you are publishing for broadcast, you should keep your sound uncompressed and choose Raw from the publish settings. 44khz 16bit is CD quality audio.

download the sound tutorial (file name: 1sound.fla)
right click on the file (control-click for Mac) and select to download to your drive.