Problem when I try to insert pagination

Thanks for @PieterGoosen for his help, I found the solution for my problem.

In my functions.php, I construct the next function:

function mod_query($query){
   if ( !is_admin() && $query->is_main_query() && $query->is_category('6')){ //My Category ID
        $query->set('posts_per_page',2);
    }

}

add_action('pre_get_posts','mod_query');

And I needed one file, category-blog.php where I build my html code and use the php code

 if (have_posts()){
    while(have_posts()){
        the_posts();
        //.....my code.....
    }
 }

And my navigation it’s works!

Thanks so much @PieterGoosen for your help.