Select an item to transform
Do one of the following:-
To transform an entire layer, make the layer active, and make sure nothing is selected.
Important: You cannot transform the background layer. To transform it, first convert it to a regular layer. -
To transform part of a layer, select the layer in the Layers palette, and then select part of the image on that layer.
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To transform multiple layers, do either of the following in the Layers palette: link the layers together, or select multiple layers by Ctrl-clicking (Windows) or Command-clicking (Mac OS) more than one layer. In the Layers palette, you can also Shift-click to select continguous layers.
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To transform a layer mask or a vector mask, unlink the mask and select the mask thumbnail in the Layers palette.
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To transform a path or vector shape, use the Path Selection tool
to
select the entire path or the Direct Selection tool 
to
select part of the path. If you select one or more points on a path,
only those path segments connected to the points are transformed. -
To transform a selection border, make or load a selection. Then choose Select > Transform Selection.
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To transform an alpha channel, select the channel in the Channels palette.