I must have missed it. I wonder if it's now too late.
Edited to add:
Well, I went back through all the screens on Expedia to see when I was asked for any special requests. I did find it this time. It says "I have a special request", it's in really small writing and you have to click on the link to bring up the box to type in your request. Ugghh, I wish I had seen it when I booked the room.