Here are some examples of how to use it in a sentence:
* Я сижу на стуле. (Ya sidzhu na stule.) - I am sitting on the chair.
* Он сидел за столом. (On sidel za stolom.) - He was sitting at the table.
* Дети сидели на полу. (Deti sideli na polu.) - The children were sitting on the floor.