Can someone help me how to get a ícone in a fã club?

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

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