It's impossible to guess what you are seeing without URLs or screen shots. Please provide these details.

Don't know what a URL is or how to provide a screen shot.

Hi - If you don't know what an URL is, lets begin with first principles. A URL is a website address, such as google.com. It may be you have not quite understood what Thunderbird does. It does not provide email service, it is a program that manages the email you already receive, to download it onto on your local computer. So you choose what email service you want to use - not Thunderbird. First choose whether to use Gmail or Yahoo or some other email service, and create an account with that service. If you have an email account already that's great. Then set Thunderbird up to log in to your existing email account, and collect the emails for you. (That is where Thunderbird tries to make it easy by offering to detect what email service you might be using, but you need to know which and pick the one where you have set up an account.) Honestly you do not even need Thunderbird if you are happy to use Yahoo or Gmail or whatever email by connecting to the Internet each time you want to read email - you can read and send from online. Thunderbird lets you read and send from your local computer as well. I hope that makes sense. Good luck, Agnes