2 loops in blog homepage

You can use this code to get 3 posts from category Featured

$args = array(
  'category_name' => 'featured',
  'posts_per_page' => 3
);

$featured_posts = new WP_Query( $args );

if ( $featured_posts->have_posts() ):
  while ( $featured_posts->have_posts() ):
    $featured_posts->the_post();

    // Here you can use the normal loop functions like 'the_title()' to display your
    // 3 posts from the category 'Featured'
  endwhile;
endif;

After this code, it’s important you place the following line:

wp_reset_postdata();

After looping through a separate query, this function restores the $post global to the current post in the main query.

Edit
You can use the following code to get a loop with pagination enabled:

$paged = ( get_query_var( 'paged' ) )? absint( get_query_var( 'paged' ) ): 1;

$args = array(
  'posts_per_page' => get_option( 'posts_per_page' ),
  'paged' => $paged
);

$posts = new WP_Query( $args );

// Merge the two results
$posts->posts = array_merge( $posts->posts, $featured_posts->posts );
// Increase the post_count to display all the items in the merged posts array
$posts->post_count += $featured_posts->post_count;

if ( $posts->have_posts() ):
  while ( $posts->have_posts() ):
    $posts->the_post();

    // Here you can use the normal loop functions like 'the_title()' to display your
    // posts from the category 'Featured'
  endwhile;
endif;