Heh, alright seeing I've been helping a lot of people and friend learn to digital color, I figured I would just post up my self-taught tip to digital coloring that I've found worked wonders. You can even ask the people I've taught the trick to that probably still use the same method today. I know I still do.
Step one) Download GIMP, it's a free art program that's somewhat easy to use if you know what your doing. I've learn many people think it's confusing, but you eventually get the hang of it after you've played with it for some time.
Step Two) Upload the artwork. This artwork can be a sketch art, line art, digital art, ect. Just get it up