How do i add animations to the Horizontal axis?

I was trying to make a good movement system for my first game and I tried to implement animations to the game but I don't know how, this is my code:

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4.  
5.  
6. public class PlayerControler : MonoBehaviour
7. {
8.     Rigidbody2D rb;
9.     public float velocity;
10.     public float jumpVelocity;
11.     [SerializeField] LayerMask groundLayer;
12.     float timeInTheAir;
13.     public float maxJumpTme;
14.  
15.     // Start is called before the first frame update
16.     void Start()
17.     {
18.         rb = gameObject.GetComponent<Rigidbody2D>();
19.     }
20.  
21.     // Update is called once per frame
22.     void Update()
23.     {
24.         //Move with "A" and "D"
25.         rb.velocity = new Vector3(Input.GetAxisRaw("Horizontal") * velocity, rb.velocity.y, 0);
26.        
27.  
28.      
29.  
30.  
31.         //Raycast
32.         RaycastHit2D raycastGround = Physics2D.Raycast(transform.position, Vector2.down, 0.25f, groundLayer);
33.  
34.         if(raycastGound)
35.         {
36.             maxJumpTme = 0;
37.         }
38.         //Jumping with Space
39.         if(Input.GetKey(KeyCode.Space) && maxJumpTme < 0.2f)
40.         {
41.             maxJumpTme += Time.deltaTime;
42.             rb.velocity = new Vector2(rb.velocity.x, jumpVelocity);
43.         }
44.            
45.     }
46.  
47. }
48.  

also i want to fix my raycast because its broken, the problem is when i jump i only can jump once and the i cant jump anymore.