The Gradient Editor

The gradient editor is the panel where you create your custom or preset gradient. There are two ways to open up the gradient editor. Firstly, with the gradient tool selected you can right click on the canvas, and the editor will open up. Or you can left click on the gradient drop down menu on the options bar. The following gradient editor window will show up.

This is the list of default preset gradients. You can change the preview of the presets to: text, thumbnails or lists which displays the presets into a different format.
This creates a new preset gradient. The new preset will appear in the gradient preview.
This allows you to change the gradient from solid to noise. The noise gradient contains random colours from a specified range.
This is the colour sliders, notice there are two sets of sliders: the top two and the bottom two. The top two are the transparency sliders you can change opacities of each of the sliders. To create another transparency stopper you can click anywhere in between the two stoppers. The bottom two stoppers allow you to change the colours. Dragging the stoppers blends the colours together and clicking in between the two stoppers creates a new colour stopper.