How do I tilt my Spaceship and make it go up and down?

Hello, I want my spaceship to tilt left and right whenever I 'sidestep' with it. But I'm not sure how to make that work :/ I would also like to make my spaceship go straight up and down, when pressing 'space' and 'ctrl', but my If-statement doesn't really work >_> any suggestions?

 using UnityEngine;
 using System.Collections;
 
 public class FirstPersonController : MonoBehaviour {
     
     public float movementSpeed;
     public float mouseSensitivity;
     public float tilt;
     
     public float upSpeed;
     public float downSpeed;
     private float normal = 0.0f;
     
     CharacterController cc;
     
     void Start() {
         Screen.lockCursor = true;
         cc = GetComponent<CharacterController>();
     }//start end
     void Update() {
         
         //Rotation
         float rotLeftRight = Input.GetAxis("Mouse X") * mouseSensitivity;
         transform.Rotate(0, rotLeftRight, 0);
         
         float rotUpDown = Input.GetAxis("Mouse Y") * mouseSensitivity;
         transform.Rotate(-rotUpDown, 0, 0);
         
         //Movement
         float forwardSpeed = Input.GetAxis("Vertical") * movementSpeed * Time.deltaTime;
         float sideSpeed = Input.GetAxis("Horizontal") * movementSpeed * Time.deltaTime;
         
         if(Input.GetButton("Jump")) {
             normal = upSpeed;
         }
         
                                  //(left/right, up/down, forward)
         Vector3 speed = new Vector3(sideSpeed,0,forwardSpeed);
         
         speed = transform.rotation * speed;
         
         cc.Move(speed * Time.deltaTime);
     }//update end
 }//class end