Easy.... Looking at the firearm from the rear.
Gun shooting left and you want to move your shots to the right.
Rear sight has to be moved to the right
or
Front sight has to be move to the left
Gun shooting right and you want to move your shots to the left
Rear sight has to be moved to the left
or
Front sight has to be moved to the right
Hope this helps... One of the above posts has it all wrong and will make you crazy if you do it his way at the range.
John