All combat actions - close or ranged - require a successful roll to hit home and do harm. As with any other roll, your character's Attribute and Skill dots are combined as the basis for your dice pool. For example, a Strength of 3 and Brawl of 2 adds to five dice. This pool represents your character's raw combat potential.
Other factors apply, however, such as any weapons he wields or special effects that he attempts or initiates. That is, a number of bonus dice are added to your pool equal to the rating of the tool or effect used. So, a sword rated 3 adds three bonus dice to your pool. A mysterious supernatural trick that benefits your character's attack may add four dice. These modifiers increase the total number of dice in your hand.
Meanwhile, your character's target more than likely tries to avoid being harmed, and may wear protective gear of some kind. In close combat, the target's Defense trait and the rating of any applicable armor worn is subtracted from your attack dice pool. If penalties imposed on your character's attack exceed your character's Attribute + Skill + any bonuses involved, the action is exceptionally challenging. The only way to accomplish it at this point is to make a successful chance roll.
Example: The aforementioned character brings a sword into close combat. His 3 Strength and 2 Weaponry grant five dice. His sword, rated 3, adds three bonus dice to that pool. His opponent has a Defense total of 4 and wears armor rated 1. That means five dice are removed from the attacker's pool. The attacker is left with three dice.
In ranged combat, dice pools for attacks are composed in much the same way. The attacker's Dexterity and Firearms (or Athletics for a thrown weapon) are combined. The rating of the gun or weapon used is then added to that pool.
Example: If your character has 2 Dexterity and 1 Firearms, you have three dice in your pool. If she fires a gun rated 4, four more dice are added for a total of seven.
In the case of Firearms attacks, however, a target's Defense does not usually apply. It's not subtracted from the attacker's pool. People don't try to avoid arrows or bullets like they do punches or sword swings. They run and look for protection, instead. The exception is if Firearms-based attacks are staged within close-combat range; within a yard or two.
A target's armor does apply against ranged attacks.
Example: Continuing from above, the Defense score of the target is not subtracted from the dice pool of your character's Firearms-based ranged attack. His 1 point of armor is, however. Assuming the target stands stock still, without diving for cover, your dice pool loses only one die. You're left with six dice in your hand.
A target's Defense does apply to thrown attacks made by rolling Dexterity + Athletics, such as with a rock or spear.
