I am using the cable that has a monitor plug and 2 colored cables (red and white, which are audio) which cable would I need to connect these to head jack speakers ( computer speakers)

I’m thinking about buying a 360, but I live in a dorm and don’t have a tv. I know I can use the vga cable to connect it to my computer monitor, but how can I connect computer speakers to the 360, preferably without involving my computer at all?
Thanks alot!