Nothing focuses the mind like the imminent prospect of death in combat. Although characters are free to engage in an infinite range of activities during combat, the reality is that most actions will be centred on killing and avoiding being killed.
An action that focuses on attacking someone works exactly the same as any other action. The action's focus must be stated, appropriate and available cards played, dice rolled and used cards returned to the deck or otherwise dressed. Each action still has to beat the resistance to succeed and that is set by the target's resistance action.
The only notable difference between a normal action and an action attacking someone is that there tends to be a weapon involved. Firearms and other projectile weapons have wildly varying ranges and capabilities. Weapons such as hand grenades can attack multiple people at once. Even simple weapons like daggers and clubs can have their own special keywords and behaviour.
Understanding the differences between each weapon and how that affects their use is the key to fast and efficient combat.