Could you post more of that instruction sheet? The instructions are mostly hidden. It 'sounds like' it is using the compose panel to have an 'out of office' message. That seems a bit dicey, as it leaves your email open to anyone. Tell us more and I'll try to help. My recommendation, though, is to consider a screensaver and lock to protect your PC contents.

This is where I got the information from: https://amitlyblog.wordpress.com/2013/06/12/how-to-set-up-an-out-of-office-auto-reply-in-thunderbird/#:~:text=How%20to%20set%20up%20an%20out-of-office%20auto-reply%20in,template.%2017%20Click%20Ok%20to%20close%20the%20filter.

So is the display layout of my Thunderbird correct?

Thank you for your reply by the way David

Yes, you're fine. Just follow the steps to create the template - but you must keep computer on throughout. As an alternate suggestion, if you have webmail for your account, you might check to see if the webmail offers an out-of-office (sometimes called 'vacation response'). If that exists, you may find it quicker and more consistent, as if you're away for a day or more, your computer may shutdown for various reasons.