This Thread is for people who are First starting flash. If you are already an experienced Flash user, then please DO NOT leave comments that are negative towards the beginner community.
In Flash, You need to go to the top of the screen to the sub-menu 'FILE' and go down to the second Sub-Menu named 'IMPORT'. Then click on 'IMPORT TO LIBRARY'. Another window will pop up with the option to pick a file to import into the flash library. Pick the sound file you would like to Import. If the sound file you want to use is grey, or unimportable, that means it is probably a format not compatible with flash. If you really have your heart Set on that particular file, I'd suggest you use a sound editing program like AUDACITY or GARAGEBAND if you have a mac.
After that, Drag the audio file you wish to use from the 'LIBRARY'(which can be accessed by going to the sub-menu 'WINDOW' or by clicking cntrl+L) onto a layer in the timeline.
Next, Go to the top of the window(For PC. for Mac go to the top of the screen) where it has a Sub-Menu called 'WINDOW'. Click on the sub-menu and click on the option called 'PROPERTIES'. A window should pop up towards the bottom of the screen(Unless of course you have opened the window before and moved it to a seperate part of the screen).
Then click on a frame withing the layer on the timeline that has the sound file in it. The properties window should change it's contents and have a drop-down menu called 'EVENT'. Change the event to 'STREAM' and you should be set for the rest of the flashes you make with the computer you are using.
So I hoped that helped anyone struggling with Syncing issues. If you have any more questions, leave them on this Thread or PM me.