Step 4. Make the lines wiggly!

'Filter', 'Distort', 'Ripple' ...Now you will get a warning message about needing to rasterize the layer, this is ok so just let it do it.

4.jpg

now you have the little 'ripple' window. play around till you've got something you like, I went for 65% & large.
and when you hit OK ...voilà screen full of wiggly wave lines