how to import other programming language support on windows emacs ?

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hi folks, 
 i'm using emacs under windows and it looks cool. however i need emacs 
 to recognize Flash ActionScript files(.as files) and support its 
 syntax highlighting. i downloaded a "actionscript-mode.el" from 
 another guy's website, however i still dont know how to install 
 this .el to make it work with emacs. any help pls ? 

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Never end on learning~