[photoshop-beginners] I'm having trouble with selections

 

I'm trying to fix a person's smile in a photo I took.
The person is missing two teeth, so I copied two from the other side of the mouth and pasted them on a new layer.
Then I choose Image\Image Rotation and flipped it horizontally.
At some point I must have deselected it, so I went to the layer, right clicked and choose Select Pixels.
I can move the layer using the Move Tool.
What I can't do is figure out how to rotate the selections, or layer for that matter.
If I choose modify Selection, I can rotate the selection, but not the image…

How do I rotate the layer or the part of the layer I have selected?

Thanks

Kelvin

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