I have successfully installed a plug in DYNAMIC HEADERS
A new menu has appeared HEADERS – so far so good thought this was going to be easy
When I click on any of the options within the new menu (DIRECTIONS, ADD NEW FILE, MANAGE FILES, SETTINGS, ABOUT) I get this
It looks like wp-content/header-images/ is not writable or does not exist.You will need to create this directory make this directory writable in order for the plugin to work.Maybe This Article from WordPress will help.
and when I look at the article, I am suddenly right out of my depth
Yes that article is correct. The easiest way is to ftp into your server (your hosting company should be able to talk you through this) and then create a new directory called header-images in the existing folder wp-content if the header-images does not exist. You may also need to change the file permissions on the header-images directory so it is writeable. Do this by right clicking on the folder from your ftp client and clicking on file permissions.