Ski movement / rotation

Hello, I try to make a simple ski game

I modeled a ski terrain, and for ski player, I found this tutorial here:

And I use this script below for player movements - it works very well. But I would like to replace lateral movement by rotation.

Could you show me how to do this on base of this code?

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class PlayerController : MonoBehaviour
    public float moveForce;     // Force applied when we move left or right.
    public Rigidbody rig;       // A referene to our Rigidbody component.
    // Called 60 times a second.
    // Similar to the Update function, but used for physics calculations.
    void FixedUpdate()
        // Get the horizontal input.
        // 0 = nothing
        // 1 = right
        // -1 = left
        float xInput = Input.GetAxis("Horizontal");
        // Add force based on our input.
        rig.AddForce(Vector3.right * xInput * moveForce);

Thanks for your help