Need help with turtle beach headset connecting to computer monitor!!?

I play xbox 360 on a flatscreen dell computer monitor that has hdmi input but NO sound or speakers. i really want to play with sound so i was thinking about getting a turtle beach headset. the problem is that i can't connect the turtle beach headset to the monitor but i have to connect it to a tv that has sound. the computer monitor has no sound input output so what do i do!!