The parameters are URL,ID,Window parameters. Your new window will open "page" with an id of "my_gallery.swf." The ID is used to insure new window always opens if the spawned windows are already open or to refer to if from other windows.
Not sure what you're doing with the SWF, but if it's what I think it is, something like this might work. The scenario is to pass the name of the .swf to a php script in a new window.
function my_win(the_flash) { var day=newDate; var id=day.getTime(); var url = 'yourscript.php?f=' + the_flash; var params = 'width=700,height=400,scrollbars,resizable'; var win=open(url,id,params); return false; }
Always allow your windows to have scrollbars and be resizable, it may look good to you but you never know what your user's environment will be and it can hide vital controls if you don't.