I`m trying to set up my thunderbird email account on my iphone.

There are no Thunderbird email accounts. Thunderbird is email client software just like the client you are trying to add your real email account to on your phone. You enter the server settings for your email provider. You can copy those settings from Thunderbird but Thunderbird has nothing to do with checking your email on a phone.

Thank you! I try to put it this way. How can i read my mails on the iphone? When i use other emails i can log in to my account when i`m on their webpage. This mozilla confuses me.. Line

You have an email provider. This is not Thunderbird. You access the email account that you have with your provider on devices like phones and computers using an email client software. You setup the client software with the details for your provider like server names and ports. Your phone should have come with an email client software installed. Use that to check your email. Thunderbird has nothing to do with checking your email on your phone.

You can always use your providers web mail account and log into that using a browser like Firefox or Chrome. Then there is no need for email client software.