I want to use GIMP to create the palette automatically from a series of colors in squares that I have ready, but I can't find the option in this series of instructions:
Import a New Palette
The Import a New Palette dialog has a few controls, but these are straightforward. Firstly click the Image radio button and then the drop-down menu beside it to ensure that you have selected the image you wish to use. If you have made a selection to select just part of the image, click the Selected Pixels only tick box.