The first image tells you what to do as you click on your email address on the top of the hamburger menu then click Manage Account. I suppose a image example could have been added to article in case the text instructions was not clear enough. Your second image is indeed the menu button the article is referring to.

https://support.mozilla.org/en-US/kb/add-secondary-email-address-firefox-accounts

If you are logged in then you can click the arrow next to your email address at the top of the "3-bar" Firefox menu button drop-down menu. You can click Settings in the "3-bar" Firefox menu button drop down or open about:preferences in the address bar to find the Sync tab.

Thanks for all that, but I am not quite there yet. Apologies but I am Autistic and I can be very very literal. As it is I can't see any email address at the top of the menu. I have enclosed an image. I am logged in to the Mozilla Support Website. The second image is what I see when I click on aettings in the first image of the menu. I tried "about:preferences" and got the same page as the second image shows. What is SYNC? what does it have to do with this situation. I only have one PC and I don't have a mobile phone, so what would I have to Sync with? I dont even have wifi in the house I live in. It is very remote here and all I have for access is Satellite Broadband. Sorry to be such a dinosaur!

Yours Sincerely, Ms Jacq Felis.