The composite cable for the Xbox has RCA Phono Male connectors for audio L , R. Depending on the speakers you choose, you may need an adapter or not. Sometimes the speakers ship with an adapter.
Buy the speakers you want, if your available connection options dont work, tell us what you got and we will tell you what you need to make it work.
or, when you decide to buy the speakers (assuming at a physical store), take the Xbox cable with you and see if it will work.