Traducción:Estamos sentados en la mesa de atrás en el restaurante.
Several people asked about using the Spanish gerundio - sentando is this sentence, similar to what is done in English. First of all, in English "we are sitting" and "we are seated" are two ways of saying the same thing in English in a sentence like this. In Spanish, the gerundio is normally reserved to talk about something that is actively in process..or is developing. Having a butt in the chair...simply being seated...is not a very active process, and therefore it would be unusual for a Spanish speaker to use the present continuous in this case. I'm not saying it is never done...there are areas where the influence of English is quite strong on the Spanish language, so it wouldn't surprise me to hear it on occasion, but I would guess you could spend years in Spain without hearing it used this way...by a native from Spain.