This step is pretty self explanatory. You scan the inked drawing so that you can get a copy into your computer. It is important that you scan the image in as straight as possible to avoid having to adjust it in the computer.
Incidentally, if you do not have a scanner, you can also simply take a photo of the drawing and import that into your computer. While this method will suffice, be forewarned that it will require level adjusting and a lot of angle adjustments once it's in your computer. That is because lighting will play a huge factor in a photograph, which wouldn't come with direct scanning.
There's just not much more to say about scanning. It's straight forward.
This is part of the process that can be painstaking. After scanning the image into the computer, you will import it into Adobe Illustrator (Photoshop works too). Once the drawing is imported, you have a few options. You can either use the pen tool to trace each line (preferred for detail), or you can do an Object trace. Whichever method you choose, what you are essentially doing is creating a digital vector version of the drawing. This allows the image to be re-scaled without losing quality. This is important because of the size skate deck art needs to be (9in x 33in).
As you can see from the screenshot, illustrating the image begins to create what looks more like a comic book illustration. Of course, you'll notice something missing...color. That comes in the next step.
In the illustration step, you just want to make sure that you account for all the detail you want in your image. The more detail you incorporate here, the more detail the end result will have. Keep in mind that if you want a more photo realistic end result, a lot of these lines will go away when you begin to color things in. These lines will then server as highly detailed "guide lines" for shading and things like that.