I would like to have a full screen header image on my archive page for my blog posts (in this case they are Promotions for a hair salon) but I can't work out how to do this. I also tried to create a Promotions page and then put in a shortcode for my blog posts but I couldn't get the posts to show up like they do in the Salient default masonry grid which I love (as on the archive page). So - Could you help me with either of these issues:

a) show me how to get a full screen header image for my category archive like on my other pages, or

b) show me how to add a post shortcode that will look like they do on my archive page (so I can have a full screen header on a 'page' displaying my posts)

Thank you!