Go to more actions > manage > attachments > upload your .swf file > when upload is complete click on view > copy the url from the address bar and close the file
Navigate to the page where you want to add the flash file > click on edit > insert > more gadgets > search for "anyflash" > select the swf 2.0 gadget > paste in the url of your flash file that we coied earlier > customise the size of the gadget to match the dimensions of your .swf file and save.
After a few refreshes if you still can not see the file on your site:
Click on edit > left click on the gadget block on your page > click on the properties link > click in the text field where the url is and navigate to the end of the url > change the attredirects from 0 to 1 or vice versa > then resave > problem solved! :)
Let me know how you get on!