I have looked for how to perform unarmed strikes, but i can’t find it. I have looked in weapons and attacking but it does not say anything
An unarmed strike is treated as a default Damage effect with the same rank as your Strength attribute
As described by the Damage effect:
Strength provides a “built-in” Damage effect: the ability to hit things! You can apply effect modifiers to the damage your Strength inflicts, making it Penetrating or even an Area effect! You can also have Alternate Effects for your Strength Damage; see the Alternate Effect modifier for details. Like other Damage effects, a character’s Strength Damage is close range and instant duration by default.
And the Strength ability itself:
[...] Your Strength rank applies to:
- Damage dealt by your unarmed and strength-based attacks.
Whenever you want to just hit something unarmed without using a specific power, you'd resolve that as an attack with a Damage effect ranked equal to your Strength, with a range of close and instant duration. You would use your Fighting ability to determine your attack modifier for close attacks, as usual, and you could improve that by taking ranks in the skill Close Combat: Unarmed if you wanted to be specifically skilled at unarmed martial arts.
Just to add to Carcer's answer, "Unarmed" does default to straight Strength damage, but for the purpose of the Close Combat skills, your GM may feel that other items will match up, like natural weapons (teeth, claws, tails, etc) or weapons that attach directly to your limbs, like brass knuckles, in the same way that Close Combat (swords) applies to swords that you don't have built into your character.
As per What kind of Close Combat skill do I need for grab-like moves?, you technically don't get Trips or Grabs with Close Combat: Unarmed, although I'd argue that it's not overpowered in the least.