Colliding for my character

I've made that code for my character, I can not add any colliding to it with other objects. Rigidbody wont effect it by it's default. Can anyone help me out?

The script:

 using UnityEngine;
 using System.Collections;
 
 [RequireComponent(typeof(CharacterController))]
 public class char_movement : MonoBehaviour 
 {
 
 
 
 public float moveSpeed = 15.0f;
 public float turnSpeed = 45.0f;
 public bool built = false;
 public float grove = 8.0f;
 public float velo = 1.0f;
 public float jumpStr = 10.0f;
 public bool onjump = false;
 public float timer = 1.0f;
     void Update()
     {
         CharacterController controller = GetComponent<CharacterController>();
        transform.position -= transform.TransformDirection(0,1.0f,0) * grove * velo * Time.deltaTime;
         
         if(Physics.Raycast(transform.position,-Vector3.up,1f))
         {
             built=true;
             Animateable();
         }
         else
         {
             built=false;
             animation.Play("jump");
         }
         
         if(onjump)
         {
             timer-= 3.0f * Time.deltaTime;
             transform.position+=transform.TransformDirection(0,2.0f,0)*jumpStr*Time.deltaTime;
             jumpStr-=0.7f;
             if(timer<=0.0)
             {
                 onjump=false;
                 timer=1.0f;
                 jumpStr=10.0f;
             }
         }
         if(built)
        {
           velo = 0.0f;
            if(Input.GetButtonDown("Jump"))
          {
              onjump=true;
          }
        }
        
        if(Input.GetKey(KeyCode.W))
            transform.position += transform.TransformDirection(0,0,1.0f) * moveSpeed * Time.deltaTime;
        
          if(Input.GetKey(KeyCode.S))
            transform.position += -transform.TransformDirection(0,0,1.0f) * (moveSpeed-10.0f) * Time.deltaTime;
 
 
          if(Input.GetKey(KeyCode.A))
              transform.Rotate(Vector3.up * -turnSpeed * Time.deltaTime);
 
 
         if(Input.GetKey(KeyCode.D))
             transform.Rotate(Vector3.up * turnSpeed * Time.deltaTime); 
        
        
        if(!built)
            velo += 1.0f * Time.deltaTime;
        
        }
     
     
     //-------------------
     void Animateable()
     {
         if(Input.GetKey(KeyCode.W))
        {
            animation.Play("walk");
        }
         else if(Input.GetKey(KeyCode.S))
        {
             animation.Play("walkback");
        }
 
 
          else if(Input.GetKey(KeyCode.A))
        {
                        animation.Play("walk");
        }
 
 
         else if(Input.GetKey(KeyCode.D))
        {
                        animation.Play("walk");
        }
        else
        {
            animation.Play("idle");
        }
     }
     //--------------------
     
     
 }