This video shows a cool "mental model" to remember how the Hit, Wound, and Save rolls work in Warhammer 40,000, as well as how some of the special weapon abilities work, like Lethal Hits, Devastating Wounds, Sustained Hits, and Anti-infantry.
This is just one small part of how to play Warhammer, but it's a tutorial on one of the most important and confusing aspects: the combat dice roll, in both the shooting phase and fight phase.