Discussion post format

My professor wants us to use paste and match style for our discussion posts but I cannot find it anywhere. I emailed them and they tried helping but I don’t even see the edit tab that they are referring to.

Has anyone had to do “paste and match style” for their discussion posts and can talk me through how to do that? Maybe I’m just blind and missed an easy button but I literally cannot figured out and I’ve even googled it and searched the FAQs.