If neone can please tell me how to turn a unit into a hero I would be really grateful. Or just how to let a regular unit use hero abilities is what I'm really looking for.
I don't think you can. But you could turn a hero into the normal unit, by changing the model, voice, projectile...
You can make a unit have hero abilities by changing the ability. There's a true/false field for "is this a hero ability". However, making it be able to level the ability would need triggers.