Snow around border

Hey guys & girls,
I am a flash newbie and have a template designed, you can see the template here . notice there are three boxes. i wanted to add the snow affect to my template found in the tutes. but i only want it in the backround, so that it doesent fall on my boxes. i was told i had to do this with mask layers well getting frustrated and stuff couldnt work out how to do it.
Any help would be much apreciated and you can either pm or email me or post back thanks alot.
Regards .: G :.
P.s. can someone tell me how to make the first home link work with the text ArgH Thanks…