The millennium is not the year 2000 but is a period of time, 1000 years that Christ will be present on the earth administering rule over earth. He will become King of the earth taking the position away from the Devil who is now locked in a bottomless pit. As King he will rule with a rod of iron and expect total obedience. This may sound oppressive but in actual fact is nothing more than He deserves. He will have banished sin and will have set up the earth as it was in Adam and Eve's day, before the ground was cursed. There will be no more weeds or thorns, no man-eating animals everything will be at peace with each other.
The reason Christ is taking time to rule the earth for a thousand years, which on the face of it seems a little odd is because when man is Judged in the final judgement we will not be able to make up the excuse that if we had Christian leaders we would not have sinned. Even today people are saying that if we had Christian politicians the world would be a better place. This is nonsense and during the millennial reign Jesus proves this to a greater degree. Without the Devil there to tempt people, and Christ ruling as He would have us live, you would think that everything would be alright, but as we read further when the devil is loosed from the pit, humanity revert back to how it was.