Banner making can be accoplished many ways. One, you can take a picture you like, and resize it or crop it to be reasonable, not massive in size or dimensions. Then, maybe add text, such as your name, or a quote you like. Or, maybe add other pictures, made small enough to fit in the picture, and make a sort of collage. Or, maybe use just several small images, and put them in one blank image, one next to another.
Those are only a few suggestions, so let your imagination flow FREEEEEE!!!!! XD XD