This is a post that will be shown on all pages and in a Block. To do this just create a new post in your Home menu and set it to display on all pages and define a block for it and there you go.
Limit Posts
You can limit the posts to display only a defined amount of post/menu item, just edit the menu item "News" and define a number fo Limit and that's it. If there are more posts than the limit set a paging are will appear in the bottom of the page.
Partial Content
For news you can use partial content. To separate the header of a post from the rest of the content just insert a Horizontal Line when you edit the content and that's it. for e.g. here is the end of the header cos here is the horizontal line.
