Using SMTP with two-step authorisation?

Using SMTP with two-step authorisation?

Most of the time I use Thunderbird to access my emails from Zoho but since I allowed two-step authorisation I can't send any emails, with the error:

Login to server smtp.zoho.com failed.

How do we get past this?

Also, I can't find out how to turn off two-step authorisation... is it somewhere really obvious that I've overlooked?

Thanks