Legal Question in Immigration Law in Colorado

Are you currently within the US or outside the US?

And is your greencard a two year or ten year card? And do you intend to keep your greencard status?

Assuming you want to maintain your status, you need to reenter as a greencard holder. If you have left the US already, you can work with the nearest US consulate to reenter the US.

If you haven't left, you need to file to renew your card before you leave. Even if the card doesn't arrive before your trip, this will assist in reentry.