Ok I need help. I'm trying to beat zant but I don't know how to do that...

It means transform into a human and slash him with your sword.
Zant has many stages, each of which copy the boss stages from the other temples (except the final stage); so try to recall how you beat the boss of the temple he is copying. Also, the Poe locations are far to many to list here. If you search Google for "Poe ghost locations" you should be able to find a guide for such a thing.

1. Zant has loads of forms :

PART 1:
Use you gale boomerang to knock him out of the air, then attack him with
your sword.

PART 2:
Put on your iron boots and block his attacks, when he gets tired and slumps
over move in and strike (take off you iron boots before you move in).

PART 3:
Zora Armor & Iron boots on, clawshot ready, wait for him to reveal himself
from behing his own head, claw him over to you and attack. (When there are
four heads watch to see which one he is under and swim towards it).

PART 4:
Monkey miniboss, roll twice into the pole he's standing on and attack him.

PART 5:
Hit his ankles with the Ball & Chain, this will make him shrink, attack him
with your sword when this happens.

FINAL PART:
Jump out of the way of his spin attack/combine harvester style move, and
attack him when he's slumps over like from part 2. After all that HC 8 is
sitting on the throne.

2. The Poe souls are located in various regions across Hyrule, you must be in wolf form and have your senses up to detect him.