How do I play as Catwoman in Batman: Arkham City?

I have redeemed to code via xbox 360 marketplace and downloaded the content, but where in the game do I get to play as Catwoman?

many thanks guys.How do I play as Catwoman in Batman: Arkham City?
When you reach certain points in the game, you are specifically able to play as Catwoman. Her segments are almost like side-missions, but they still tie into the main story.How do I play as Catwoman in Batman: Arkham City?
you can play as catwoman once you progress to a certain point in the story mode. its somewhere around a little past the halfway mark of the game. once you play with her then you will be able to switch in and out of characters at certain markers on arkham.How do I play as Catwoman in Batman: Arkham City?
You can start playing as catwomen once batman falls into the trap of joker and gets drugged which could kill him, then you start as catwomen so its somewhere in the middle of the game.

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