The ad says Todoist lets you set an email as a task with one click
can some one tell me how?
When using the Todoist extension with your browser, click on the TD icon (beside the address bar) where you will be able to click the "add task" button at the top right. At the bottom of that new popup, you will see the "add email as task" or if you open it on a website "add website as task".
Please let me know if you have any issues with accomplishing that.