It's easy. When you're typing a comment you should see a little "add media" link. Click it and there should be a sidebar that pops up. Search for an emote like "Twilight Seriously" for example; or even "Twilight Sly" . Seriously, you didn't know how to do this? Well now you do. But for the record, I don't know if the "add media" thing is always there on mobile devices. So keep that in mind.