Love the browser, however one of the things I use my browser for is to save web pages for Evernote. There are extensions for Firefox and Chrome but there appears to be nothing fro CCleaner browser (or any extensions at all for that matter).
The CCleaner browser is Chromium based, so any Chrome extensions should work happily with it.
Just add them as you would with Chrome.
How do you add extensions? On Chrome i'd go to 'Get Extensions' then choose extensions to install, but going to 'Extensions' in CCleaner Browser shows no available extensions nor is there a 'Get Extensions' link.
If you go to the webstore https://chrome.google.com/webstore/category/extensions in CCleaner Browser then you should be able to add the extensions from there.