that is a vector, you either use a vector based program (illustrator for example) or the pen tool in photoshop (vectors made in ps arent real vectors, their immitations, but get the job done). and if your going to post, atleast make a comment on the image :P

any way, i think there are too many colours, its like a sensory overload. You may want to use only a couple colours on the background, and parts that dont matter as much as the center peice... the person.