Dont expect to draw complex backgrounds like cities or buildings.Most gfx artist share stocks.BUT they are not free all the time.You can google them,I have Developed good friendships with gfx artist and they been very good to me.Only pros can really create backgrounds.Im not talking about brushing a little splatter here and there or using grunge brushes or light effects.I mean creating objects and places,People.Find a GOOD GFX community and you will get to the promised land.