Change transform.position into addForce or velocity

Hi, I'm new to Unity.

I'm trying to make a VR maze with terrain stamp map but the character(camera) is passing through the wall. So I tried to search the solution and I finally realised that using transform.position code is not appropriate for this.

Here's the code.

public class PlayerWalk : MonoBehaviour { public int playerSpeed;

 // Start is called before the first frame update
 void Start()
 {
     
 }

 // Update is called once per frame
 void Update()
 {
     if (Input.GetButton("Fire1"))
     {
         transform.position = transform.position + Camera.main.transform.forward * playerSpeed * Time.deltaTime;
     }
     
 }

}

How can I change this transform code into addforce or velocity code, please?

Thanks.