The marquee selection tools allow you to create selections based on standard geometric shapes, such as ellipses and rectangles.
Selection tools
There are several marquee tools you can use to create pixel selections:
Rectangular Marquee Tool—creates a rectangular or square selection.
Elliptical Marquee Tool—creates an elliptical or circular selection.
Row Marquee Tool—creates a rectangular selection of a set pixel height which spans the entire image's width.
Column Marquee Tool—creates a rectangular selection of a set pixel width which spans the entire image's height.
To create a pixel selection:
With one of the above marquee selection tool selected, drag on your page.
To set the width of a row/column selection:
With the Row Marquee Tool or Column Marquee Tool selected, adjust the Height or Width , respectively, by either dragging on the vertical slider or by tapping on the number. Then simply enter the precise value and parameter.