Here is their web page on that: https://community.talktalk.co.uk/t5/Articles/Email-settings-to-access-TalkTalk-emails/ta-p/2204399

No, it didn't solve my problem. However, I currently send and receive emails in Thunderbird using gmail.com, but I want to be able to send and receive them using: talktalk.net. What do I need to change to do so?

The URL I posted has the settings to do that. Are you wanting to switch from Gmail to talktalk? Just create a talktalk account alongside the Gmail account. Let me know if you need more specifics.

Hi! David: Thanks for being so patient with me. However, I still can't get it right. So, I'm about to copy three pics from my clipboard which might explain what I've been trying to achieve. The pics might help explain what I've been unable to write and help you to understand. I have been trying to copy the pics for the last hour or so and can't. I continue to use gmail.com - but thanks for your help. Regards - John.

If you use Windows, there is a free snapshot tool. Once the stuff you want a screenshot of is on screen, press the Windows key and the shift key and the 's' key. A little menu will appear at top of screen. Click the leftmost icon and you can then use mouse to drag and highlight the area to capture. Click when done and an edit window will open and there is a 'save as' icon in upper right.