You can manually rotate a selection or layer using Free Rotate.
To Free Rotate:
To rotate a selection or layer (rather than the whole image), do either of the following:
To rotate a selection, make a selection in the image.
To rotate a layer, on the Layer palette click the layer name.
Choose Image > Rotate > Free Rotate (Ctrl + R) to open the Rotate dialog.
In the Direction group box, select the rotation direction: Right or Left.
In the Degrees group box, select the number of degrees to rotate. To enter a value between 0.01 and 359.99, select the Free option.
To apply the rotation to all layers rather than just the current layer or selection, mark the All layers check box.
Click OK.
Note: When you rotate a selection, the selection becomes a floating selection and the original image is unchanged.
Scaling and Transforming Images