Logo, Cover Photo, Title & Description
Once you add the theme to your blog, got to the settings page (screenshot below)
http://yourawesomeblog.com/ghost/settings/general and upload 1920px X 410px cover photo (the mentioned size is the ideal size but you can experiment with different photos); Within the same page upload a logo (ideally not more than 100px in height).
Icons from Font Awesome
Check Font Awesome for over 350 icons you can use if you want to add more social icons or even in your articles.
For example if you want to add a star icon then you can simply do it by adding
<i class="icon-star"></i> anywhere in your article