@Jeffrey375 You won't see the coded email address Airbnb assigns on the listing page and Contact Host just lets you sned an Inquiry. It soundslike you are in the midst of an active reservation, or is this a place you already checked out of? If the reservation is active, just go to your messaging stream with the ost, and her coded email address should appear to the left of the messaging- you have to scroll down to see it. At least that's how it appears on the host's account, I've never been a guest, so not sure it appears in the same place. Also I should think it would appear somewhere on your reservation itinerary.
But I'm not sure what point there is in sending a photo of the distance of the TV to the couch- I'm quite sure the host is already aware of the set-up. Why not just send the host a suggestion? And I can tell you that your advice for a bigger TV may not go down well. Just because you want a bigger TV doesn't mean it's anything that past guests have found to be a problem.