In the Inventory (Most Recent Tab) tab, put a weapon in your Action Bar and select it. Press [Use Item] to attack.
Press [Lock on target] to lock onto an enemy. Your camera and attacks will focus on them.
Maneuver behind enemies to backstab them for increased damage.
Unlock more fighting abilities in the skills menu.
Perform defensive actions to prevent or reduce incoming damage. Most of them cost stamina, so keep an eye on your stamina ring.
Perform a Dodge Roll by pressing [Evade] to evade enemy attacks.
While equipped with a shield, block attacks with [Block and Parry]. A well-timed block will parry the enemy's attack. A parry requires no stamina, interrupts the enemy's attack, and fills their stun bar.
Once full, the enemy becomes overpowered and is stunned temporarily.
Equip a bow and select ammunition from your inventory to engage in ranged combat. Aim for the head or the enemy's weakspot to do more damage. You can detonate explosives at range with arrows, or throw grenades which detonate on impact.
Equip a staff or wand to unleash magical power. Wands don't require ammunition and have a short cast time. Staffs need spell charges or channels as ammunition and require mana. Magical spells can only be cast with staffs.
You can avoid combat completely by sneaking. Crouch down by pressing [Sneak] and enter bushes to remain hidden from the enemy's sight. All bushes hide you.
You can spend skill points to learn the Sneak Attack. Sneak up behind unsuspecting enemies and unleash a Sneak Attack by pressing [Contextual Action] while hidden.