How do you create a second account? You contact your email provider and set it up. Once you have that established and working then you add it to Thunderbird. From the Menu Bar select File-New-Existing Mail Account If your Menu Bar is hidden press the Alt key to reveal it. There is no such thing as a Thunderbird account. Thunderbird is email client software running on your computer. Email accounts and addresses come from email providers. You add the info for those email accounts to the Thunderbird software to help manage your mail.