For this one you're going to need Photoshop and a picture, the picture can be of whatever you want, as long as you make it black and white. If your picture is not already in black and white you can make it black and white by going to image, pressing mode and then pressing grayscale. Now your picture is in grayscale. As you can see on my original picture (the one up highest) I had to do that to make my picture grayscale. Then you start coloring over the gray picture with a paintbrush on low opacity, if you don't have low opacity you will just paint overt everything, and trust me, it will NOT look good! As you can see on my colored result (the one at the bottom) the colors wasn't perfect, but it looks natural, and that's the point! To get your picture to look as natural as possible.