So I got the marked for death shout, but im not really sure how it even affects people besides turning them purple, anddddd the throw voice shout does nothing to my enemies, not even so much as to distract them

Pretty sure throw voice is meant to be used out of combat to help with sneaking.

Marked for death is an interesting one, because it lowers their armour rating so you can do more damage to them

Mark of Death is a debuff shout(you do more damage to them), and throw voice is used to distract enemies while you're sneaking.

ahhh alright, thanks guys!