Composition Input render layer I am planning to make a plane with heat distortion which is the same as http://www.blenderguru.com/tutorials/how-to-create-heat-distortion/#.VI5GlivF9jI
I followed all the steps but i can't add the input render layer in the compositor for the plane. Is there any neccessary thing needed to be done before using the compositor? It is my first time using compositor.
Here is the file , http://www.mediafire.com/download/mswmux40sugxjs3/help+plane.blend
You need to activate the compositor by checking the "use nodes" option in the node editor's menu header (make sure you have the composite tree selected!) It looks like this:

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This has not been done in your file.