The first one is called WP Random Header. It simply randomly chooses an image from a folder called “header-image” it wants you to create in your wp-content folder. Not a big deal if you know how to use FTP or cPanel interface.
The second one and the one I am using now is Add to Header. It is fantastic and even though developed long ago, still compatible. He did a great job with it. It requires a bit of HTML knowledge, but it’s not overwhelming. Basically you need to be able to find the URL for the media in your media library (or URL if you are hotlinking) and you need to know how to use the img src command. If this confuses you, ask a web designer friend to help you or hire me! This does way more than just this, and is a fantastic addition to any site. You will find other uses for it as well.