How to mark a training as completed?

Hi, I have started a Zwift training plan recently - i’ve read somewhere that a training session that is done outdoor could be marked as completed. how can this be done?

You have to do it on Zwift app, not zwift companion, when the upp shows you the training you have next, press “view entire plan”, then look for the session you did outside, and down right, there is the button to mark it “I did it”.