?? What the fuck are you talking about? There is no source code to flash dude. How do you know it is in flash? There is souce code to PHP which can make flash on the fly. Look http://macromedia.com
That is the company the makes flash product. Down load the FlashXP 30 trial. It is fully functional it just don't work after 30 days if you don't register it.
Then you can get a better idea of what flash is.
For a tut on how to use it. http://webmonkey.com
The flash 5 tut will teach you enough about this one to have you up in no time.