Well, first off, what the guys said before ^. Get a clean signal coming in first, use a pop-shield, etc.
But dude, you should really not be smoking a joint while shouting/screaming/singing. And i would stand up instead of sitting. If you´re gonna sit, then sit up nice and straight.
I think your shout sounds pretty ok actually!
Try working on breathing techniques, and open your mouth more when doing high pitched screams/higher shouts.
Good luck man!