PLEASE WHERE´S THE ERROR?? C#SCRIPT

It sais :¨error CS1520: Class, struct, or interface method must have a return type¨

public class NewBehaviourScript : ModifiedStat {
	private bool _known;

	public Skill() {
		_known= false;
		ExpToLevel = 25;
	    LevelModifier = 1.1f;
	}

	public bool Known {
		get{ return _known; }
		set{ _known = value; }
	}
}

public enum SkillName {
	Melee_Offence,
	Melee_Defence,
	Ranged_Offence,
	Range_Defence,
	Magic_Offence,
	Magic_Defence,
}

On line 4, you need to explicitly say nothing is returned:

public void Skill() {