I think there is some confusion on what exactly you are asking. If you are asking how to display an image then you load it as dbox showed and then use the surface.blit function (at least regarding pygame). If you are talking about actually creating pixel art, then this question isn't related to python at all. You create it just as you create any other art; with a paint type program (paintdotnet, graphics gale, photoshop).
There are no short cuts to creating pixel art. In fact I'm pretty terrible at it myself. If however you are interested in devoting the effort, you can't find better than these two communities:http://wayofthepixel.net/http://www.pixeljoint.com/