Clip this layer and rename it to Folds.
Go to the toolbar and select the Rectangular Marquee tool an make a rectangular selection as shown in the next screenshot. Note that you should not cover the complete diagonal line, but leave the beginning and end untouched (marked here in red):
That was the bit I had trouble with. It was a few weeks since I did that tutorial and can't remember how I did it. I know it was something simple that I was doing wrong. Did you clip the layer? I think it might have been that which I forgot to do.
I think I had clipped it but the layer I had clipped it to wasn't clipped to anything. That was the only bit I had trouble with, the rest was straightforward I think.
not yet, will have a go later seeing as the weater is poo
i'm just recording my little sisters violin with the new mic and trying to get a lead set up so i can record straight from the keyboard.... I set it up so that the sound came out of the PC speakers but there was a delay, and she wasnt happy about that..... so off to my adaptors/wires/sockets/plugs collection to see what i can do
an make a rectangular selection as shown in the next screenshot. Note that you should not cover the complete diagonal line, but leave the beginning and end untouched (marked here in red): 
