no worries.
filax: by dither brush I am reffering to a mode in pro motion ( which can be done in psp and ps too I guess ) called 'dither' on which you can set patterns of dither and when you paint, it automatically ommits the 0 dither squares and paints the 1 squares. So you don't have to do manual dithering all the time. Of course, once you've dithered a bit as you want it with the dither mode, you switch back to normal painting and do any detail work you want on the dither, gradient it in and out of places, add noise so it's not only pattern dither, depends on what you want to do.
similarly, darken and lighten mode are modes in pro motion where when you click with your brush at places, instead of placing down the colour you've selected, it darkens the pixels beneath your pointer according to how much you've set the darken brush to in the options. This is a good tool, but it needs careful consideration in usage, as this is not photoshop, this is pixel art. Careful placement of pixels and very delicate control is paramount here. darken and lighten brushes are useful for when you've pixelled large areas of a texture, and then want to give shape to it by darkening slices or whatever of it without upsetting the detail work or repainting. In pro motion, you simply select the area you want to darken as a brush, and then click it once or twice to darken it. Then you tweak and perhaps dither in and out and voila, now it's darker, but it's not destructively edited.
Hope all this helps. You won't find paint modes in graphics gale, ms paint or the like. You will in deluxe paint, personal paint ( amiga ), gfx2 ( there's a windows build now ) and of course, Pro Motion, which I suggest.