By going to the “Appearance” panel when you customize your theme, you are presented with many options that can let you change the colour scheme of Purify, as well as showing/hiding different features such as enabling comments or showing links to your social network sites.

Background color of the Sidebar.
Text and link color of the Sidebar.
Background color of the whole page. This will only be visible if “No Background Image” is selected.
This is the background color of each post, both on the index page and on each permalink page.
The main text color. Used on everything that isn’t a link and not on the sidebar.
The main link color that is used for the headers of each post and all links within posts.
Color for all the “meta tags” that are associated with every post. E.g. “permalink” and “notes”. Remember that this color will be faded by 50% and show it’s full color when it is hovered.
This is black by default. The separator is the black line that is used to separate each section on the sidebar. This color is faded at 20%.
This is black by default. The separator is the black line that is used to separate each section on posts. This color is faded at 20%.
Upload an image here that will replace the heading on the sidebar. Useful if you have a logo, fancy font image etc. For this to apply, Sidebar Header must be checked.
This already has a default which is the subtle canvas texture. Any background you upload will repeat. For some good background patterns that repeat - check out subtlepatterns.com
Check this option to have an image instead of a text heading on the sidebar.
If this is checked, the background will revert to use a single color, which can be set using Background Color.
This will make the social icons on the sidebar white. They are black by default. Useful if you wish to have a dark sidebar background color.
This will make the post icons white. They are black by default. Useful if you wish to have a dark post background color.
This will make the tag and type filter buttons on the sidebar white. They are black by default. Useful if you wish to have a dark sidebar background color.
This will make the more and back to top buttons white. They are black by default. Useful if you wish to have a dark background color or image.
This will make the subtle post border white. It is black by default. Useful if you wish to have a dark background color or image.
This needs to be checked in order for your Facebook comments to appear. Once this is checked, enter your Facebook App ID to complete setting up Facebook comments.
If this is checked, the social media bar will show underneath the pages on the sidebar. The social media bar is a row of circle buttons that can give users one click access to your profiles or other website. Simply submit the following in order to have the links show up in the social bar.
The sidebar is default position fixed, meaning it won’t move when the page scrolls. However, if you have a lot of pages and a large description / blog title - this means content on your sidebar may not be visible to users with small resolutions. If you enable a static sidebar, then the sidebar will scroll with the page allowing for all sidebar content to be visible.
If you wish to have comments on your Tumblr, enter your disqus shortname here to activate comments. To get your disqus shortname, sign up to disqus.com to receive one.
If you wish to track google analytics stats on your blog, sign up to google analytics and place your Google Analytics Web Property ID in here to active analytics.
You need to enter your Facebook APP ID to enable Facebook comments on your blog. To obtain one, follow this guide up to where it says “modify Tumblr theme” (that part is already taken care of by the Purify theme). Enter your Facebook ID to enable Facebook comments.