Can someone help me how to get a icono in a fan club?

unless tu created the club tu cant change the icono on your own. make a pick on the spot asking other fans for their opinion and to give them a chance to enviar new ideas as well. once the fans have chosen tu can message papa o dave and they will change it
for más info (and i do encourage tu to read it cause this is just the basics that i put down here) read this article:
link tu will find your pregunta answered at number 17!

and tu should read the whole thing cause dammit its pretty good!