The marquee is an extremely useful tool which can perform many tasks which this tutorial will outline. First, lets select your region, in this case we'll be using a oval marquee.

When you've selected your region, you'll notice a dotted box appears. This is the bounding box for your selected region. Place your cursor inside this box and you'll see your cursor changes to a move cursor.

To move your selection, press and hold the spacebar or and then use to move selection to another part of the screen. When you are finished release the spacebar or to complete the move.

You'll also see eight smaller gray boxes around the perimeter of the bounding box, these can be used to scale your image. Move your cursor into one of these boxes.

Press and hold the spacebar or and then use to scale the image. When you are finished release the spacebar or to complete the move. The boxes to the north, south, east and west, will allow you to only scale in one direction, vertically or horizontally.

Move your cursor over one of the boxes on the corners.

Scaling with these boxes allows you to scale the selection in both directions at once.

If you press , then select 'Edit', you can see a list of actions you can perform to the selection, such as cutting, pasting and cropping.

If you press , then select 'Transform', you'll be able to scale, rotate or flip your slection.

If you press , then select 'Adjust', it will show you a list of the various adjustments you can perform on the selection.

If you press , then select 'Filter', it will show you a list of the various filters you can apply to the selection.

Finally, when you are finished with the marquee, press , then select 'Edit', then 'Deselect' to apply your changes.