Paris abducting Helen is important because this what made the Trojan war in the first place.
Trojans war draft dodgers. This is important because then they will know what resources they have.
Agamemnom breaks a truce with both armies while Paris is gone.
Achilles best friend, Patroclus, takes Achilles armor and looks like Achilles and ends up getting killed by Hector. This makes Achilles furious and goes into battle with the determination to avenge Patroclus.
Achilles is furious ready to slay Hector. Achilles ends up killing Hector. This is important because this is what makes Achilles come up with a plan to go in to Troy.