Spirals are created by moving the sliders to various positions. You use the speed slider to slow-down (move right/smaller numbers) or speed-up (move left/larger numbers) the drawing algorithm.
Colors can be adjusted by picking a color or entering a valid color name like red or #ff0000, an rgb color such as rgb(255,0,0) (again red) or an rgba color such as rgba(255,0,0,.5) where the last value is opacity (or transparency).
Spirals can be saved by clicking the Save menu item. Save will open a browser window with a snapshot of the spiral. Using your browser's right-click context menu chose the Save picture as... item.