MCX360 (and indeed, any game on the Xbox 360, be it downloaded or disc-based) will check for updates as soon as you start it up, provided that you have an internet connection. You need at least a Silver LIVE profile (the non-paid one) for this.
If there is an update available, you will be prompted to install it. Simple.
Ok so when i first played the game on my xbox it preformed a system update needed to run the software does that mean it should update?
That was actually an update to your console's software, if it was a system update. But yes, as I said, if you have at least an internet connection and a Silver Xbox LIVE profile, you will receive updates when they are released when you start the game up.