Im new to fashion and help?

I'm a guy and have just started getting into fashion. Im kind of confused as to what I should and shouldn't wear and how to wear it. Also the whole matching thing or not matching. Is GQ a good magazine to read? I really don't have a certain style I'm going after. Sometimes I like to dress prepay, sometimes classy, sometimes I like wearing Jordans. Is there any good websites or forums also? I'm 17 years old also and like all the major clothes company's like Gucci, Louis Vuitton, D&G, Ralph and Lauren, Banana Republic, etc.