For your "Hem" posts you have to do a post query. In your theme's index.php put this above your loop:
<?query_posts('cat=3'); > if your news category has a category ID 3.
To make a welcome post on the home page make a post sticky. It wil show on top.
On page.php (Blog - all other posts) you have to do multiple loops. Make a category of "blog-sticky" and give this category to the post you want to show up on top.
for the first loop (blog-sticky) put this right before the loop:
<?php $my_query = new WP_Query('cat=4&posts_per_page=1'); ?>
and begin your loop with this:
<?php while ($my_query->have_posts()) : $my_query->the_post(); ?>
for the second loop (all other post minus news and blog-sticky) put this right before the loop:
in this example the category blog-sticky has an ID of 4