I thought it might be good to post a summary of how combat works.
Agillity + Alertness
Agility + Attack Skill (usually Guns, Melee, Ranged Weapons, or Unarmed)
Everyone can do one action per turn without taking any penalty. Every additional action you take causes a -1 step penalty on every roll that turn. Those with “Fightin’ Type” get one free non-combat action per turn of combat (including Dodging!).
The target number to hit someone changes based on what’s going on.
Standing Still: 3 (target unaware of attacker)
Innate Defense: Agility Roll
Block: Agility + Melee or Unarmed (costs 1 Action)
Dodge: Agility + Athletics/Dodge (costs 1 Action)
All-Out Offense: Block or Dodge + 2 steps (costs 1 Action)
If you take a defensive action during your turn, it applies to the next attack against you. If you take it in reaction to being attacked, the action penalty applies to your next round. You have to decide if you’re defending before the attack is rolled.