Hey Paul,

You might find this video helpful: https://youtu.be/ICJ9B88bzYI

This is at the add media page before you press insert.

ATTACHMENT DISPLAY SETTINGS

Alignment
Link To

http://

When you put add media and add a picture or banner then where it says to add the website or link you put it there next to the http: and pick the link to custom url, attachment, page, it gives you the options to pick usually it's custom url.
I hope it helped. Good Luck!!! :)

I guess it will depend on how the banner is created.

But banner is just an image (if this is not so, make it an image by taking a screenshot), so you can then link it the usual way used for any image.