Select a sound or group of sounds and cut or copy. Cut will delete the selection and store the cut in the clipboard. Choose paste to paste the selection you just cut. Copy copies the current selection to the clipboard (without deleting the selection). You can select portions of sounds, as well by clicking on the bottom selection area of the sound and dragging left or right. Cut, copy and paste menu items are located on the "Edit" menu or by right clicking on a selection.
(The image above shows a selection of a part of a sound.)
To select a part of a sound, simply click on the bottom ‘selection’ area and drag the mouse left or right.