To create a new image, select File › New. This opens a dialog in which you can make settings for the new image.
If desired, select a predefined setting called a Template.
Note: Custom Templates
To create a custom template, select Windows › Dockable Dialogs › Templates and use the controls offered by the window that opens.
In the Image Size section, set the size of the image to create in pixels or another unit. Click the name of the unit to select another unit from the list of available units.
(Optional) To set a different resolution, click Advanced Options, then change the value for Resolution.
The default resolution of GIMP is usually 72 pixels per inch. This corresponds to a common screen display and is sufficient for most Web page graphics. For print images, use a higher resolution, such as 300 pixels per inch.
In Color space, select whether the image should be in color (RGB) or Grayscale. For detailed information about image types, see Section 17.6.7, “Image Modes”.
In Fill With select the color the image is filled with. You can choose between Foreground Color and Background Color set in the toolbox, White or Transparency for a transparent image. Transparency is represented by a gray checkerboard pattern.
When the settings meet your needs, click OK.