Photogenics uses a few concepts that you might not have come across before. The first is the concept of a "paint layer". To visualize this, imagine painting with real paints on a glass sheet. You can place the glass over an existing image, and paint on it without worrying about messing up the image underneath. You can wipe the paint off the glass if you make a mistake, and if you decide to get rid of everything you painted, you can always just remove the glass and the original is still intact underneath.
Paint layers work the same way. Drawing on top of an image doesn't affect what is underneath until you say so. You can remove unwanted portions of paint by drawing with the right mouse button. If you decide that you aren't happy with any of the paint, clear the paint layer and you are back where you started.
The other main concept in Photogenics is that of Paint Modes. In a typical image processing application, to emboss part of an image, you would select that area using selection tools like polygons and magic wands, then apply the emboss effect to the image, so that only the area you selected was embossed. With Photogenics, you simply change the paint mode to Emboss, and paint over the area you wish to emboss. Wherever you paint instantly becomes embossed. You don't need to create tedious masks, or undo the effect, modify the mask, then redo again to see the changes. If you decide that you want to change the angle or strength of the emboss, there's no need to undo, change the options, and redo it again, with Photogenics you just go the paint modes options and drag the sliders, the image updates in real time.
Imagine that you painted something, but weren't quite happy with the colour. It might be too dark, too light, or just the wrong colour altogether. Photogenics features an Experiment mode that lets you change the colour of what you have drawn. When in this mode, selecting a new colour results in the old one being replaced, in real time. This concept applies to paint modes too. In experiment mode, changing what mode you are painting with updates the image to look as if you had painted it in the new mode. You can use this to cycle through all the paint modes in Photogenics, and see which ones give the best effect for your image.