Collision not working

Hello, im new to unity and I have a problem with collision with my player and terrain. The player just goed through the terrain! I added a box collider to my main character, and the trigger option is unchecked on both I also used a script that checks is collision working but it does not say anything in the debug log. I tried to attach a rigidbody to my character but then I cant controll my player normaly. Does anyone know what is wrong?

function OnCollisionEnter(collision:Collision){

if (collision.gameObject.tag == "Char")    

{ 

    print ("yay"); 

} 

}

Thank you for your help

Collision signals require a rigidbody on at least one of the objects. If you're not already, you should probably use a Character Controller object (should come with one of the importable unity packages if not loaded by default).

With the character controller, use

OnControllerColliderHit()

The character controller comes with movement, jumping, and a few tweakable settings to provide a smooth and intuitive movement.

if you can't use a character controller, you'll need a rigidbody to get a CollisionEnter. It might help to adjust the gravity, restrictions, or drag in the inspector.