Load swf by passing variable from html page

Hi, i’m new to flash cs4 and action script entirely, and i’m stuck on the final stretch of a project i’m workng on.
My Problem Is: I have a main swf movie…in which i want to load another swf by passing variable from html page
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in flash 8 in as2

my code is that…
var topnavigation = _root.topnavigation; // Will load top navigation.swf
drop.loadMovie(topnavigation);