The judgement is done by Christ and his Apostles acting on his behalf (seeing that there are billions of people and one Christ you can imagine how long it would take if there was only one Judge and billions of people).  
 
When the judgement comes we will all have been resurrected both righteous and unrighteous we will stand before Christ or an Apostle of Christ and bear witness of our doings in this life.  
 
We then will inherit the just rewards of our actions and inherit our level of glory (or in the case of Devil his Angels and the few Sons of Perdition that rejected the Holy Ghost after having a knowledge of God, they will inherit no glory but be banished to outer darkness for all time)!  
 
The judgement is a day of joy, the day we get to return to our Father in Heaven if worthy and gain our exaltation and become like Him through the atonement of Jesus Christ.