How do I add an email to tasks in Trident?

How do I add an email to tasks in Trident?

Hi, 

I'm trialling Trident to see if it works better for me than the browser version. It's a nice idea and looks quite refined, so I'd like to be able to use it.  

My first question is: how can I add and email to a task? I can't find any obvious way, but imagine there must be one. 

Thanks, 

Peter