Instructions
Access the back panel of the Xbox 360. Locate the "HDMI" port located on the lower right hand side of the console.
Plug an HDMI cable straight into the port, with the longer flat side of the connector facing up.
Locate the "HDMI" input port, located underneath the left side of the Dell ST-2010B monitor as it faces you. Plug the other end of the cable into this port.
Turn the monitor and console on. Allow the console to auto-detect the ideal resolution of the monitor, which it will do by default. The monitor will adjust its resolution in accordance with HDMI's extended display identification data (EDID) protocol.