use tc to drop a marked packet

Hi lartc denizens,

I've never used tc before.  I've tried to figure it out but never made 
it very far.

I want to drop packets marked with hex 19.  How would I do that?

Here's what I've got so far and am not sure this part is right:

tc filter add ... handle 0x019 fw classid 1:1 action drop
               ^^^                         ^^^

Thanks for any help,
Mike Wright