Here it goes.You castled queenside and your opponent castled kingside.You move your queen to the kingside,with your bishops/knights/rooks pointing over there.However,you should never forget that attacking with pieces only is not going to work much.Pawns.Those pawns all have a queen waiting inside them.Their power is unmatched in right locations.So,what to do??The game will show you.
As you can see,there are few simple things to do when the two sides castle opposite sides.However,you dont need to exchange all minor pieces.Just enough to open up the lines for pawns to advance
1)Attack with pawns very quickly.Dont lose tempo.
2)Open up the area you are going to attack so that the pawns can advance.
3)If you exchange your attacking pawns with your opponents' defending pawns,move your pieces there to attack.
4)Knights(if you have any) are useful in stopping the enemy pieces from entering your positions.
5)Place the bishops(if you have any) at a place where they will both help defending your king and they will be aimed at enemy king.
6)Keep the lines around your king as closed as possible.
7)Create weaknesses in enemy pawns.(Doubling,leave behind,etc).
These will help you in future games where you castle at the opposite sides with your opening.