To extract images, all you have to do is go to Google/Bing/whatever search engine you have, search up whatever you have in mind for a banner, and copy/paste the link into the form. You o have to think about what that image is going to be used for. Usually images with solid-colored, simple backgrounds are best for things to put on the banner, while the background depends on the kind of banner you get. Some offer different styles (bubbles leaves, fire etc), and some let you pick a background image. To add your characters, you have a couple of options. If your character resembles a particular character from anything (Red and Gold, for example), you can usually just find a picture of them. For characters like Arceus and Dormant, you could probably find an image of a person that resembles them, and use that. Or, for Arceus you could just find her in Pokémon form. But if you can't find a good image that resembles Dormant, you could probably go to the fan art open request thread and see if anyone can make something that suits your needs. If this was confusing, I would recommend PM/VMing Eeveelover824, TheSketchQueen, ~BrightStarVictory~, or another artist from the forum to clarify, since a lot of them are very good artists, IMO. Not that others aren't, I just remember them off the top of my head.