Well, topic is solved as far as I see, but for further readers:
Download icon, upload to site (FTP or even WP media uploader), copy icon url link, go to Graphene Options/Top Bar options/, in “Add social media Profile” choose type:”Custom”, paste icon url in “URL” and type in description, click on “add this social…” -> Save -> Done.
For putting it on some other place, use Josh advice 🙂