Here are some examples:
* S'asseoir sur une chaise: To sit on a chair.
* S'asseoir à table: To sit at the table.
* S'asseoir par terre: To sit on the floor.
Important: "S'asseoir" is a reflexive verb, which means it uses the reflexive pronoun "se".
Here are some variations of "sit" that might also be useful:
* Asseyez-vous! (formal): Sit down!
* Assieds-toi! (informal): Sit down!
* S'installer: To settle down (more like "make yourself comfortable")