Okay this tutorial will teach you how to take a photo and change it to look like it was drawn.
1. First we start of by opening our image that we'll be using. In this case my Girlfriend after being prettied up to go to the beach.

2. Now we duplicate that layer by going to Layer -> Duplicate Layer. We name this layer "top"
3. Now with the layer top selected (in the layers pallette) you need to inverse the image. You can do this by hitting ctrl + i or Image -> Adjust -> Invert

4. Okay now with Layer Top still selected in the layers pallette you need to make the Image Grayscale instead of RGB. You can do this by going to Image -> Mode -> Grayscale

At this point it doesnt look like we're really doing much to the image but in fact we are and this next step shows it.
5. On the Layers Pallette change the Layer Mode to "Color Dodge" This will give you a pure white screen. Or at least it should - don't worry if the image your using has a few black spots on it, it will still turn out okay at the end.
6. Now for the final step. You need to add some Gaussian Blur to the image. The ammount depends on how you want it to look. You can get to the Gaussian Blur by going to Filter -> Blur -> Gaussian Blur
When you have completed the tutorial you should have an image like this.