Hi I found this class and I made some adjustments in order to use it.

Here is my class:

Public Class SlideShow
{

    public String notiDescription { get; set; }
    public String notiID { get; set; }

        //1st Product Photo
    public List<Product__c> Prodphoto {get; set;}
    public String P_imageTag {get; set;}
    public Integer P_strt=0,P_ed=1,P_len=0,P_i=0,P_indx=0;
    public String photo_tmp {get; set;}
    
    //2nd Product Photo
    public List<Product__c> Prodphoto_two {get; set;}
    public String P_imageTag_two {get; set;}
    public Integer P_strt_two=0,P_ed_two=1,P_len_two=0,P_i_two=0,P_indx_two=0;
    public String photo_tmp_two {get; set;}
    
    //3rd Product Photo
    public List<Product__c> Prodphoto_tree {get; set;}
    public String P_imageTag_tree {get; set;}
    public Integer P_strt_tree=0,P_ed_tree=1,P_len_tree=0,P_i_tree=0,P_indx_tree=0;
    public String photo_tmp_tree {get; set;}

    //slideShow Photos
    public List<Noticia__c> photo {get; set;}
    public String imageTag {get; set;}
    public String photoUrl {get; set;}
    public Integer strt=0,ed=1,len=0,i=0,indx=0;
    public String tmp {get; set;}
    
        //slideShow Photos
    public List<Metrica__c> metrica_photo {get; set;}
    public String metrica_imageTag {get; set;}
    public String metrica_photoUrl {get; set;}
    public Integer metrica_strt=0,metrica_ed=1,metrica_len=0,metrica_i=0,metrica_indx=0;
    public String metrica_photo_tmp {get; set;}
    

   public void SlideShow()
   {
      strt=0;
      ed=1;
      len=0;
      i=0;
      indx=0;
      Integer count_foto = [SELECT COUNT() FROM Noticia__c];
      Integer rand_foto = Math.floor(Math.random() * count_foto).intValue();  
      // Retrieve first noticia Image          
      String sql = 'SELECT image__c,Descripcion__c, Id FROM Noticia__c A LIMIT 1 OFFSET ';
      sql = sql+rand_foto;
      photo = Database.query(sql);
      imageTag = photo.get(indx).image__c;
      notiDescription = photo.get(indx).Descripcion__c;
      notiID = photo.get(indx).Id;
      strt = imageTag.indexOf('src=',0) + 5;
      ed = imageTag.lastIndexOf('alt=') - 2;
      tmp = imageTag.substring(strt,ed);
   }
      public void SlideShowDesc()
   {
      notiDescription = photo.get(indx).Descripcion__c;
      notiID = photo.get(indx).Id;
   }
    public  SlideShow()
    {
    
      Integer count_foto = [SELECT COUNT() FROM Noticia__c];
      Integer rand_foto = Math.floor(Math.random() * count_foto).intValue();  
      // Retrieve first noticia Image          
      String sql = 'SELECT image__c,Descripcion__c, Id FROM Noticia__c A LIMIT 1 OFFSET ';
      sql = sql+rand_foto;
      photo = Database.query(sql);
      imageTag = photo.get(indx).image__c;
      notiDescription = photo.get(indx).Descripcion__c;
      notiID = photo.get(indx).Id;
      strt = imageTag.indexOf('src=',0) + 5;
      ed = imageTag.lastIndexOf('alt=') - 2;
      tmp = imageTag.substring(strt,ed);
      
      // Retrieve active Metrica          
      String metrica_sql = 'SELECT graphic__c FROM Metrica__c A WHERE A.Active__c =' + 'true';
      metrica_photo = Database.query(metrica_sql);
      metrica_imageTag = metrica_photo.get(metrica_indx).graphic__c;
     
      metrica_strt = metrica_imageTag.indexOf('src=',0) + 5;
      metrica_ed = metrica_imageTag.lastIndexOf('alt=') - 2;
      metrica_photo_tmp = metrica_imageTag.substring(metrica_strt,metrica_ed);
     
      // Retrieve 1st Random Product
      Integer count = [SELECT COUNT() FROM Product__c];
      Integer rand = Math.floor(Math.random() * count).intValue();      
      String foto_sql = 'SELECT Product_Logo__c FROM Product__c LIMIT 1 OFFSET '; 
      foto_sql = foto_sql + rand;
      Prodphoto = Database.query(foto_sql);
      P_imageTag = Prodphoto.get(P_indx).Product_Logo__c;
     
      P_strt = P_imageTag.indexOf('src=',0) + 5;
      P_ed = P_imageTag.lastIndexOf('alt=') - 2;
      photo_tmp = P_imageTag.substring(P_strt,P_ed);
      
      // Retrieve 2nd Random Product
      Integer count_two = [SELECT COUNT() FROM Product__c];
      Integer rand_two = Math.floor(Math.random() * count_two).intValue();      
      String foto_sql_two = 'SELECT Product_Logo__c FROM Product__c LIMIT 1 OFFSET '; 
      foto_sql_two = foto_sql_two + rand_two;
      Prodphoto_two = Database.query(foto_sql_two);
      P_imageTag_two = Prodphoto_two.get(P_indx_two).Product_Logo__c;
     
      P_strt_two = P_imageTag_two.indexOf('src=',0) + 5;
      P_ed_two = P_imageTag_two.lastIndexOf('alt=') - 2;
      photo_tmp_two = P_imageTag_two.substring(P_strt_two,P_ed_two);
      
      // Retrieve 3rd Random Product
      Integer count_tree = [SELECT COUNT() FROM Product__c];
      Integer rand_tree = Math.floor(Math.random() * count_tree).intValue();      
      String foto_sql_tree = 'SELECT Product_Logo__c FROM Product__c LIMIT 1 OFFSET '; 
      foto_sql_tree = foto_sql_tree + rand_tree;
      Prodphoto_tree = Database.query(foto_sql_tree);
      P_imageTag_tree = Prodphoto_tree.get(P_indx_tree).Product_Logo__c;
     
      P_strt_tree = P_imageTag_tree.indexOf('src=',0) + 5;
      P_ed_tree = P_imageTag_tree.lastIndexOf('alt=') - 2;
      photo_tmp_tree = P_imageTag_tree.substring(P_strt_tree,P_ed_tree);
    }          
   
    public void prev()
    {
      if(indx != 0)
      {
        indx = indx - 1;
        String sql =  'SELECT image__c,Descripcion__c, Id FROM Noticia__c A';
        photo = Database.query(sql);
        imageTag = photo.get(indx).image__c;
        notiDescription = photo.get(indx).Descripcion__c;
        notiID = photo.get(indx).Id;
     
        strt = imageTag.indexOf('src=',0) + 5;
        ed = imageTag.lastIndexOf('alt=') - 2;
        tmp = imageTag.substring(strt,ed);
      }
    }   

    public void nxt()
    {  
      len = [SELECT COUNT() FROM Noticia__c];
      if(indx < (len-1))
      {
        indx = indx + 1;
        String sql =  'SELECT image__c,Descripcion__c, Id FROM Noticia__c A';
        photo = Database.query(sql);
        imageTag = photo.get(indx).image__c;
        notiDescription = photo.get(indx).Descripcion__c;
        notiID = photo.get(indx).Id;
     
        len =imageTag.length();
        strt = imageTag.indexOf('src=',0) + 5;
        ed = imageTag.lastIndexOf('alt=') - 2;
        tmp = imageTag.substring(strt,ed);
      } 
    }       
}

Here is my test class that for some reason only covers 27% of the class:

@isTest
private class SlideShow_TestMethod // Name of the test class, Can be any name
{         
    static testmethod void SlideShow_TestMethod()   // Name of the test method. Must be the same as the class name 
    {
        SlideShow ss = new SlideShow();   // Initialize variable for original class 
        ss.SlideShowDesc();
        ss.prev();
        ss.nxt();
        ss.SlideShow();
    }   
     
}

Thanks for all the help in advance.