Depending on how important that aspect of your listing is, @Patricia36, you could incorporate "first floor apartment" in your title; make sure your listing description notes the first floor location and include a picture of the entrance to the apartment showing no stairs. Hope this helps. Linda
Patricia there is not a specific location to indicate that your listing is a first floor listing but, if it is stairs that you are concerned about you can check the 'Stairs' box which you will find in the 'Amenities' section, as per this screenshot.....
This will then indicate to potential guests that there are stairs involved.