Saving just as Opening (see in detail - 'Opening picture' chapter). One difference is additional parameters after filename input. In saving GIF, PNG and ICO - you will be asked about 'transparent color'. When you draw picture - you can flood future transparent areas with some certain color. And then when you asked about 'transparent color' - you need to move cursor to one of area with this color and press '5' - and then in saved file all pixels with this color will be transparent. Also you can simply press Ok without pressing '5' (and selecting of transparent color) ;)