Each PÊB theme comes with buckets of appearance options. You can change these options on your customize page – located here on your primary blog, and at tumblr.com/customize/username on any secondary blogs.
There are 6 type of appearance options that can be used to customize your theme
Please note that the blog preview in the customize page may not be an accurate representation of how the theme looks on your blog, this is because tumblr doesn’t fully reload the preview when you change appearance options. It is often better to save every the options and see how they look on your actual blog.