How to create a ladder script in Unity [closed]

I tried to create a climb script and found some similar code. I would like to climb with my player on a ladder. I came up with the following:

bool canClimb = false; float speed = 1;

GameObject player;                          // Reference to the player GameObject.


void Awake () {
    // Setting up the references.
    player = GameObject.FindGameObjectWithTag ("Player");
}



void OnTriggerEnter2D(Collider2D other) { // send in the other collider (should always work)

    if (other.gameObject.tag == "Player") { // used a tag to ID collider as player
        canClimb = true;
        player.rigidbody.useGravity = false;

    }
}

void OnTriggerExit2D(Collider2D other) { // send in the other collider (should always work)

    if(other.gameObject == "Player"){
        canClimb = false;
        other.attachedRigidbody.useGravity = true;

    }
}

void Update () {

    if(canClimb == true){


        if(Input.GetKey(KeyCode.Z)){

            player.transform.Translate (Vector3(0,1,0) * Time.deltaTime*speed);

        }
        if(Input.GetKey(KeyCode.S)){
            player.transform.Translate (Vector3(0,-1,0) * Time.deltaTime*speed);


        }
    }
}

The above code will give a red mark on the useGravity in the line of player.rigidbody.useGravity. I doesn't know how to fix this.