How to blend copied portion of picture

[Jackie Matthews]

Not sure I've got my workflow correct which is why I may be struggling but how do I blend the copied portion of this picture to match the rest?  I need a bit more sky and post to put the pier in the centre of the picture so I increased my canvas size, copied the portion I wanted, used a hue/saturation clipped layer to try and match colour (this may need adjusting) but the line where the two meet needs blending but I don't know where/how to do this

[Damien Symonds]

You should have duplicated and flipped the WHOLE photo, so you had heaps of room for your masking.

[Jackie Matthews]

Ok and would I increase the canvas size before I did that or after?

[Damien Symonds]

Probably after.  Duplicate the Background layer, then extend the canvas size, then move the layer and mask it in.